If I understand your question correctly you want this

package Foo;

sub inscope {
    print "in Foo's scope\n"
}

1;

package main;

use strict;

sub Foo::outofscope {
    print "in main's scope\n"
}

Foo::inscope();
Foo::outofscope();
[download]

Although I'm not sure if it breaks when using Safe it works under use strict and is the only 'safe' way I know of adding functions to packages outside of their scope without having to do funky symbol magic.
HTH

broquaint