perl 5.8.0 is not binary compatible with 5.8.1,
but 5.8.2 is binary compatible with 5.8.0.
Since 5.8.2 is the latest and greatest perl, you should try installing that one, then come back if you have trouble installing it.
That's not going to get him anywhere, though. OS X 10.2 ships with Perl 5.6.0, and the modules he's having trouble witih are provided as part of the stock OS install. No version of 5.8 is going to do any good under OS X 10.2, unless he can scare up the source and rebuild the modules.