Hmm, if I understand your question, you don't need to get mixed up in the shady world of Perl at all ;). Just use HTML; you can use the TARGET attribute of a form to specify a named HTML window or frame where the result of the form should be displayed.

<form target="output" method="get" action="/path/to/your/script">
[download]

With this, if you have a frame called 'output', the results of your form will appear there, leaving the completed form in the original frame

HTH