A large portion of my modules are indeed Object Oriented.

I don't really see how that matters here though, and if I'm not using OOP I can't see wanting one module to inherit from another, as that is a core OOP-ism

I have, however, run into times where I want the functionality of a non-OO module to be accessable in a OO fashion. In these cases, I usually write a OO wrapper for the module, in my namespace, making liberal use of Class::MethodMaker, that I then extend as needed.

My advice when you need to do this is to keep the OO 'wrapper' module as light as possible (meaning it doesn't do anything the non-OO module doesn't do) and to extend that wrapper with yet another module that does what you need. This lets you keep pure-wrapper code away from your changes, and gives you another module to be happy that Devel::Cover gives you 100% on covering