It's possible. I maintain multiple versions for development purposes. It's fine for stand alone scripts, CGI, FastCGI ... but not mod_perl.

For the 'alternative' module, you'll want to install it in some location outside of your normal @INC and just use lib '/path/to/library/base';

You'll also want to take note that the syntax use Module version; will use that version or greater, and will not restrict it to that specific version. If you wish, you can inspect $Class::MethodMaker::VERSION and abort if the wrong version was loaded.