It's not clear from your description (to me at least) which perl you did use for running perl makefile.PL. The system perl (which, IIRC, was v5.005_03 at the time of Solaris 8), a self-built perl, or one from opencsw?

Such info (including the output of perl -V) plus an exact sequence of steps together with any errors, etc. would greatly help anyone trying to help you... ("cut and fudget with the Makefile" isn't really reproducible... :)