supporting differing versions of same perl module

Assume two endpoint URLs, one using the current and one using an old
version of a perl module foo.pm for our application. This 2008 article
shows how to prevent conflicts (old app using new foo.pm or vv)
for this situation under modperl:

    http://www.slideshare.net/shixilun/module-versioning-with-apache-1x-and-modperl-1x
    ( 2008. HTML:Mason involved )

What is the new best practice?

--
thanks,
Tom