I was having a problem installing the XML::Parser perl module on Mac OS X. The problem is because fink installs the expat library in /sw/lib, where the configuration script is not expecting it. Also, if the configure script doesn't find it, the user is not promted for the correct location.
This page describes the fix.
# perl -MCPAN -e'look XML::Parser'
# perl Makefile.PL EXPATLIBPATH=/sw/lib EXPATINCPATH=/sw/include
# make; make test; make install
The first command downloads and expands the package and opens a shell in the expanded directory.