Hi I would also like to contribute as well; I just started looking around jboss.org on how to do this yesterday;
I found the bug list for AS here:
And what looks to be an outdated dev doc here:
Is there any instructions on how to get going in an eclipse-based development environment?
The contributor agreement process is described here:
but typically you need to start out getting involved in the forums to introduce yourself to the development community as the leads will need to give the agreement an ok.
Just search the wiki for eclipse. One starting point is here:
Our eclipse based dev tools is probably the best place to start: