Just thought i'd drag this up for a little update,
I was forced into writing my own startup/shutdown control software as ShutControl started refusing to run which is annoying. At least this way my app doesn't use any of the .NET stuff so i know it'll run with only a couple of DLLs on Win 2k-7 without issues.
I've also done the discovery work for the Car2PC adaptor as the winamp plugin now refuses to talk to the headunit, i've got the protocol spec dechiphered (not as obvious as it should be) and sent some test commands and got some test data back from the headunit.
I'm now going to set about writing the interface. After that i plan to structure the program properly into discrete classes for different pieces of work, then i can consider releasing it as a DLL, or code.