Your quest reminds me of something I read in the FAQ for Zlib, (Zlib FAQ), question 12:

Can zlib handle .Z files?

No, sorry. You have to spawn an uncompress or gunzip subprocess, or adapt the code of uncompress on your own.

Note: Zlib is the basis for the module Compress::Zlib, and the basis for the gzip utility. The reason is not that these people can't code it, but for legal reasons: they can't distribute the code to do it — or at least, it'd compromoise the rest of their library. I think details of that decision are somewhere on that site. (So far, my searches for it have been unsuccessful.)

Therefore, you mustn't expect it, or likely any other perl library, to support .Z files, at least, until the patent(s) .Z is under, expire.

Update According to this site, which describes the hisory a little, the patent should already have expired in 2001.