I've been known to dabble in the firmware... yes.
As to how... well the beauty of CW is that you just install it and "go." Otherwise... it gets more complicated.
There's a thread for that... kinda long, maybe best to start from the end and read upwards.
viewtopic.php?f=31&t=44 There's a couple other threads around that are more step-by-step... search the forums for "makefile".
The latest "unreleased" changes are on my own for now. Mostly pending QGC being updated to handle the new controls scheme. Which I'm also the sole dev on, currently.
There's lots of work that can be done on the GCS side to support the project, using free tools even...
-Max