Have a look at the guts of the HTTP::Cookies module.

I suspect you should be able to subclass HTTP::Cookies, and override the save, load, and set_cookie methods.

save and load could be defined to do nothing, or to access some in-memory structure under your control.

You'd override set_cookie just so you can intercept calls to it; you'd probably want subsequently to chain to the base class's version of that sub.