Perl can do anything ASP can do (and IMHO it can do it better but that's probably what do you expect from a Perl site)

My advice: code in one language. ASP and Perl can both be used to generate HTML pages and be used to retrieve the value of a select box, like you describe, and do something with it. You're asking for a maintnence nightmare if you code part of it in one and part of it in another