All I can think of for you to do is to use realative paths. If you structure your environments such that use lib "../libs/" refers to the proper place w.r.t. either development or live, the script should compile correctly.

Consider this (sideways) directory tree

perl-code
    live
        exec
        libs
    devel
        exec
        libs
[download]

Since you are not relying on run-time vars to decide the location, I think this might solve the problem.

--traveler