Ok, thanks... but really I'm trying to avoid using eval() (or /e) in the first place.
<RANT> Seeing as Perl lets you specify regex patterns in variables used for search text (s/$pattern/), it really seems like there ought to be a non-kludgy way to interpret backreferences from a variable in the replacement text (s/$pattern/$replacecontainsbackrefs/) ... </RANT>