You might have some luck by manipulating your $PATH ENV variable. Most systems are setup to search /usr/local/bin first, then /usr/bin. That way, if you have 2 perls, one in /usr/local and 1 in /usr. the /usr/local will be found first if you type "which perl".

That said, you can get very creative by putting a symlink /usr/local/bin/perl and have it point to wherever you have activestate's perl located. It should be found first.

Other than that, you can manually delete files, rather than relying on the rpm system( yuck I hate rpm's).