only ships with Perl 5.8.4 and the modules I want to install rely on 5.8.6

You should always be suspicious of such requirements. I've seen "clever" authors requiring a specific version of perl as a way to ensure a specific version of some core module like File::Spec . More often than not such requirements are leftovers from h2xs (or similar) which by default makes the current perl version a requirement.

I've checked, and neither Heap nor Graph have perl 5.8.6 as a requirement, so 5.8.4 should suit you fine.