Hooking into GC

[MMJones via Digitalmars-d-learn]

I read somewhere that one can modify the D files from phobos and 
runtime to supply a stub for the GC. I would like to add some 
logging features to the GC.

Does this not require one to recompile phobos? I figured the 
source code was just for debugging?

I'm curious if I can really get away with modifying the source 
code in dmd2's dir and it will actually work. I guess I could try 
but I don't wanna go mess with it if it's not going to do 
anything.