I agree you should do everything in the same cgi if possible. In some cases you can't do that, though, and maybe that's the case here. (For instance, you're using a 3rd party's cgi on their site.)

Two ideas off the top of my head:

1. do something funny with javascript
2. use perl's LWP to do the post, grab the results (or part) and display to the user

I recommend #2.

Rucker