I made some coding about the music. HL support music but the main problem is HL control the music behaviour so if you start a music HL can stop it in some case. So I implemented the music using DirectShow and I have the full control of everything aswell making easy to put custom playlist. So everything was tested on HL1 engine right now. The only things I need to do is to adapt on HL2 when the SDK will be ready! We will implement a ingame player interface for our mod!
Here a screenshot of the music command from the console!