I've been wrestling mentally with this same issue for improving Object::LocalVars. The best thing I've come up with it rewriting my attributes to use Attribute::Handlers, which provides the MODIFY_CODE_ATTRIBUTES subroutine and farms out the actual attributes found to other subroutines that registered themselves with Attribute::Handlers. This, of course, requires everyone to play nice and all use Attribute::Handlers as well.

I avoided Attribute::Handlers at first because of the complexity within it -- I wanted more direct control of the attribute handling process to be sure I understood what was happening. But for interoperability, I think it's the right way to go. However, Attribute::Handlers tries to do a lot of stuff in the CHECK phase by default, and that will break under mod_perl. I believe that Attribute::Handlers will allow one to force handling to be immediate in the BEGIN phase, which I what I intend to explore as an approach.