Posted by FunnkyHDAhmad already made a section dedicated to the Music Kits on his Buy Menu.
I have an ideea , why not making CS:GO Music Kit plugin with menu ? I mean you can select what music kit you want in-game , but client-side . Btw , how can i make your music kit plugin working ? I have mp3 volume set to 0.3 , installed it correctly but nope .
As for the plugin not working, assuming you've done everything correctly, I'm not sure anymore. I've test-installed it numerous times already on vanilla CS. I even installed it on two heavily modded CS games of mine without any problems.
The only thing I could think of is it doesn't work on multiplayer which presents a problem because I can't/don't want to play multiplayer and during development I never got anyone to test it for me...