Perhaps I should have asked why you need to go to 5.8.7 of perl? Red Hat 9 was frozen some time ago and its perl version froze with it at 5.8.0-88.3. At least that is the latest .rpm for redhat 9 that I could find, and I always operate under the principle of using rpm to install on red hat 9 if it is at all possible, because it manages the installation process for you in a tried and tested manner.

The symlink idea was specifically so you could stay with 5.8.1 for the applications that might need it while creating additional versions for other uses, but so far you haven't explained why you need to upgrade above 5.8.1., which is probably the key to how to proceed.