Using the tools CPAN::Mini and cpan_grep.pl, the following findings were made:

Alternatives to Enbugger

Enbugger looks very appealing. Unfortunately it hasn't been updated in 8 years, and appears to be very broken.

Grepping through a local CPAN mirror, the following strings were found:

• /Perl_init_debugger/
  • found in Apache::DB, specifically DB.xs
• /PL_perldb.*PERLDB_ALL/
  • found in Apache::DB, specifically DB.xs
  • found in Enbugger, specifically Enbugger.xs

It looks like there aren't any alternatives. Fortunately, people have submitted several patches in the issue-tracker, so that's a hacky workaround for now.