[Distutils] Extending distutils with 3rd party build commands?

[Bob Ippolito]

I've developed two bdist commands (bdist_pkg and bdist_mpkg) for usage 
on OS X.  These commands apply to any setup.py that supports an 
"install" command, similar to bdist_wininst, so it would be nice if 
every setup.py didn't have to explicitly import something in order to 
get the commands there.

I know I can make it work with a pth file that imports bdist_pkg, but 
that seems a bit costly to do because it will end up importing a bunch 
of stuff (distutils, mainly).

Is there another way to do it?

-bob