I couldn't tell you whether this would work with IIS, though.

IIS does have some peculiarities in it's handling of PATH_INFO that you should be aware of, but there's a knowledge base article on the subject that may be of interest.

Update: If you use CGI.pm's path_info instead of $ENV{'PATH_INFO'}, it has a hack that'll return what you expect regardless of how IIS is configured.

sub path_info {
    # ....
    # hack to fix broken path info in IIS
    $self->{'.path_info'} =~ s/^\Q$ENV{'SCRIPT_NAME'}\E// if $IIS;
}
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    --k.