[XML-SIG] (Source) installation woes

[Cameron Laird]

I think I've never successfully installed PyXML stuff
from source.  What's the trick?

When I install the Win* binary for 2.1, I can bring up
Python and immediately
  import xml.parsers.expat
That's good.

Nothing I've tried on any Unix host--not RPMs, not instal-
lation of expat followed by "make distclean; configure * 
..." followed by every weirdness I could muster--has ever
given me an expat module I can import.  What's up?

I've poked around in the archives.  I found nothing I can
relate to my question.  I'd welcome a pointer that proves
this territory has already been covered.