I'm working on a module - CGI::Apache2::Wrapper - which may help in this regard. The aim here is to provide a (mostly) CGI.pm-compatible interface to certain mod_perl2 and libapreq2 methods. Currently the main one present is param(), but work is being done on others like cookie() and upload(). One of the main purposes is to assist in the porting of apps from cgi to mod_perl, so that one can say in a handler

  my $cgi;
  if ($I_want_to_use_mod_perl_modules) {
     $cgi = CGI::Apache2::Wrapper->new($r);
  }
  else {
     $cgi = CGI->new($r);
  }
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and then call methods like param(), etc. on the $cgi object, with the work of loading and calling the appropriate mod_perl2/libapreq2 modules and methods done behind the scenes.

Let me know if there's something along these lines that would be useful.