You don't want to do that.

As you've made it clear in the CB that this is out of curiosity only, here is a way to add new "global" functions to everywhere:

package UNIVERSAL; 

sub AUTOLOAD{print $AUTOLOAD};

package main;

Test();
&{'Just another Perl Hacker'}();
[download]

You should add some checking that you raise errors for "keywords" you don't know.

Also interesting to you might be Shell.pm.