As to your first question, theres a very nifty module named HashBang that:

This CPAN distribution will install a binary program on your system called 'hashbang'. You can use this program to write your own hashbang style interpreters in Perl. Let's say you've implemented a language called foo in a file called foo.pl. Put the file in the same directory as the hashbang executable. And then create a symbolic link from foo to hashbang. Like this:

    cd /usr/bin
    cp ~/foo.pl .
    ln -fs hashbang foo
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As for the rest, I wrote a simple perl language interpreter in a perl script, it's really fairly simple to do, if you're interested let me know and I get it uploaded someplace.