I haven't been motivated enough to see what the inside of a Safe::Hole->reval looks like but now that you've decided to go perlguts your first thing to do is to look at the B module. In my sig you'll notice an example of a script getting the current CV via B::svref_2object(sub {} )->OUTSIDE. I would initially recommend you read Gisle Aas' Illustrated PerlGuts, then Simon Cozens' internals tutorial and if that isn't enough descend into perlguts and perlhack. The key here is you're just walking structures. You aren't going to have to alter stuff so the documentation is to guide you in using B to walk all over.

__SIG__
printf "You are here %08x\n", unpack "L!", unpack "P4", pack "L!", B::
+svref_2object(sub{})->OUTSIDE
[download]