I decided to write this post because I didn't find any information about this theme.
Almost all the actions are the same as ones in this post: https://www.saintsrowmods.com/forum/threads/custom-radio-stations-guide.2/.

Just select Saints Row IV in the 'Game' string and click Build. Specify the path for the future archive file, enter name misctables.vpppc. Do the same with soundboot and soundscommon folders. Now place your new files into SRIV folder/packfiles/pc/cache directory. Don't forget to backup original files!!! Enjoy your ingame music! Song Name: Uploader: Length: Downloads: Loop Type: Preview: Downtown City: Maverick Hunter: 3:17: 1: Custom: Downtown City (In Game) Maverick Hunter: 2:42: 1: Custom.

Saints Row 4 Mods

First of all, it's need to download necessary utilities: https://mega.nz/#!G751GQgY!Bsyjya2WYFTGccYSIhzzFXpNzHRXv78K6XKx_TOw13M
Saints row 4 custom music downloads kpop songs

Saints row 4 custom music downloads kpop songs

Instead of Gibbed's Tools I used ThomasJepp.SaintsRow-rev121 utilities set.
BNK Tools are the same
Audiokinetic Wwise 2010.3.3 isn't working with SRIV, newer version is needed. I used 2014.1.6 version.
AudioTools folder contains new versions of ww2ogg.exe and revorb.exe that are required to be converted to an OGG format that is readable by the audio player.

So, the steps are:

Extract 3 files: misc_tables.vpp_pc, sounds_common.vpp_pc, soundboot.vpp_pc. These files are in SRIV folder/packfiles/pc/cache. Use ThomasJepp.SaintsRow.ExtractPackfileGUI.exe.
Find your unpacked sounds_common.vpp_pc. In this folder find a file like this: radio_*_media.bnk_pc ('*' means name of a radio station). Copy this file into your working folder.
Extract your radio_*_media.bnk_pc. Just drag and drop it over bnk_pc_extractor.exe.
Unpack AudioTools folder where radio_*_media.bnk_pc is extracted. Run transcode.bat. When complete, look in the folder 'Completed' - there are files that we will need later.
Use Audacity for make uncompressed wav files. Just drag and drop all your custom music over the Audacity window. Ctrl+A -> Ctrl+Shift+L -> Choose destination folder and make sure if WAV (Microsoft) signed 16-bit PCM is chosen. Click Export and wait.
Install Wwise. First I installed Authoring_Data.msi, then Authoring_Win32.msi. Maybe installation program ask you to register an account.
Perform the steps 5-10 in the same way as in the post I attached in the beginning. Don't close Wwise, it will help you in future.
In the folder C:/Users/username/Documents/WwiseProjects/project_name/.cache/Windows/SFX you can find all the files in WEM format. Don't worry, it is a Vorbis (OGG) format which we needed. Copy all of them into your working folder where you extracted all the sound files from the radio station.
Rename these .wem files into .wav files. Try to use short filenames. I used ReNamer Pro for this operation, you can use any similar program. For automating, I named files like this: 00.wav, 01.wav ... 16.wav etc. Open the metadata file (e.g. radio_klassic_media.txt). In each line that contains the path to filename, delete the part of the name so the end of filename remains. E.g., D:Moddingradioklassic03.wav. The 'Find and Replace' tool will help you.
Run command prompt. Drag and drop bnk_pc_packer.exe, press Space, drag and drop radio_*_media.txt, press Space, drag and drop radio_*_media.bnk_pc. Press Enter. When done, old radio_*_media.bnk_pc will be replaced with new one, and new file will be appeared: radio_*_media.mbnk_pc.
Copy radio_*_media.bnk_pc into sounds_common.vpp_pc folder, replace old file. Copy radio_*_media.mbnk_pc into soundboot.vpp_pc folder, replace old file.
In a folder misc_tables.vpp_pc locate the file that contains the name of your radio station. E.g., klassic_radio.xtbl. Open it with Notepad or other text editor. Approximately in the middle of the file, locate the block <Song_List>. From here the information about all the songs in the radio station begins. In each <Info> block, find the line <Length>. This is the length of the song in milliseconds. Now maximize Wwise. Somewhere at the bottom right the duration of your songs will be indicated. It is necessary to enter it in the <Length> line. But note: the information about the songs is not in the order in which you extracted them. That's what I did: I opened all .ogg files in AIMP (you can use another player). The playlist shows the duration of all songs. I compared it with the duration in the <Length> line, and based on this I replaced the duration with the desired one. So I didn't have to listen to all the songs in a row. More details the guy in this video tells (begin watching at 18 minute): But the guy uses a tracklist for SR:TT. There is no one for SRIV.
After saving, we need to repack 3 folders. Open ThomasJepp.SaintsRow.BuildPackfileGUI.exe. In the 'Source Files' string you need to select a path for unpacked folder (e.g., D:Moddingextracted-misc_tables.vpp_pc). Don't pay attention to string 'Update .asm_pc file?'. Just select Saints Row IV in the 'Game' string and click Build. Specify the path for the future archive file, enter name misc_tables.vpp_pc. Do the same with soundboot and sounds_common folders. Now place your new files into SRIV folder/packfiles/pc/cache directory. Don't forget to backup original files!!!
Enjoy your ingame music!

P.S. For fans of hard rock/heavy metal I share my custom radio stations: https://mega.nz/#!q3ZRFQxA!hcs5eltsCbXnbdVW-K86NCkpitWUUr5hD9-RjnJ3hu8 Music

Absolute Steel - Deliverance
Absolute Steel - We Sentence You To Death
AC/DC - Back In Black
AC/DC - Thunderstruck
Accept - Against The World
Accept - Beat The Bastards
Accept - Stalingrad
Airbourne - Runnin' Wild
Alcatrazz - Too Young to Die... Too Drunk to Live
Anthrax - I Am The Law
Anthrax - S.S.C./Stand Or Fall
Anthrax - Soldiers Of Metal
Black Sabbath - Danger Zone
Black Sabbath - Headless Cross
Black Sabbath - The Law Maker
Black Sabbath - Turn To Stone
Black Sabbath - What's The Use
Cacophony - Concerto
Cacophony - Speed Metal Symphony
Deep Purple - Fireball
Deep Purple - Highway Star
Diamond Head - Am I Evil?
Diamond Head - Helpless
Diamond Head - Lightning To The Nations
Dio - Breathless
Dio - Rainbow In The Dark
Doro - Burn It Up
Doro - Raise Your Fist In The Air
Grave Digger - Heavy Metal Breakdown
Halford - One Will
Halford - Resurrection
Halford - The One You Love To Hate
Helloween - Heavy Metal (Is The Law)
Helloween - Ride The Sky
Helloween - Sole Survivor
Helloween - Victim Of Fate
Iron Maiden - 2 Minutes To Midnight
Iron Maiden - Aces High
Iron Maiden - Flight Of Icarus
Iron Maiden - Iron Maiden
Iron Maiden - No More Lies
Iron Maiden - Run To The Hills
Iron Maiden - Speed of Light
Iron Maiden - The Trooper
Iron Savior - H.M. Powered Man
Iron Savior - Heavy Metal Never Dies
Iron Savior - Tyranny Of Steel
Judas Priest - Between The Hammer & The Anvil
Judas Priest - Freewheel Burning
Judas Priest - Hell Patrol
Judas Priest - Metal Meltdown
Judas Priest - Painkiller
Judas Priest - Rapid Fire
Judas Priest - Redeemer Of Souls
Judas Priest - The Green Manalishi
Judas Priest - You've Got Another Thing Comin'
Manowar - Call To Arms
Manowar - Hand Of Doom
Manowar - Kings Of Metal
Manowar - Manowar
Manowar - The Dawn Of Battle
Megadeth - 44 Minutes
Megadeth - Dialectic Chaos
Megadeth - Fast Lane
Megadeth - Head Crusher
Megadeth - Never Walk Alone... A Call To Arms
Metallica - All Nightmare Long
Metallica - Battery
Metallica - Dyers Eve
Metallica - Fuel
Metallica - Master Of Puppets
Metallica - Metal Militia
Metallica - Ride The Lightning
Metallica - Suicide & Redemption
Motorhead - (We Are) The Road Crew
Motorhead - Ace Of Spades
Motorhead - Back At The Funny Farm
Motorhead - Bomber
Racer X - Golden God
Racer X - Street Lethal
Racer X - Superheroes
Racer X - Technical Difficulties
Rage - Down
Rage - Drop Dead!
Rage - Firestorm
Rage - Supersonic Hydromatic
Running Wild - Chains And Leather '89

Saints Row 4 Custom Music