If I want to work on a package that I am having problems
with ... say I want to try to create a patch to fix a
bug ... What is the best way to go about that?

With BSD ports, I would go in to the port directory and
do a "make extract" or "make patch" then hack around in
the tree for a while then go back to the port directory
and do "make" or "make install".

I figured out that I could do "emerge" then hit ctrl-c
after it is done extracting, then hack around and do
"emerge --resume".

That works, but it seems I must just be missing a better
way.

Any tips?