Setting up a development environment for hacking GDC

[Mike via D.gnu]

I'm wondering, if some of you that do development on GDC could 
briefly describe how you set up your development environment.

I can build GDC fine, but I can't do the 30-minute build for 
every little change.  The build script is just a black box to me 
right now.  How do you guys do incremental compile and debugging? 
  I've seen https://gcc.gnu.org/wiki/DebuggingGCC, but that 
doesn't help me with incremental compile.

I could probably spend some time analyzing the build scripts and 
figure something out, but it would take me quite a while and I'd 
probably just end up with something non-ideal.

So, please take a few minutes to give me the basic rundown.  If I 
can get set up, and if you think it would help, I'll give back by 
writing a wiki page on how to get set up from a beginner's 
perspective.

Thanks,
Mike