I plainly wouldn't do that but if you really really want to, then re "I tried a combination of", you must have

1. our @ISA = qw/Exporter/;  # not 'my'!
   [download]

   as well,
2. there's some confusion going on here. You should put the first three lines in a package in the "external file". And the last one in the "main file". And what's it with those <BR>'s?!?