passing text through link?

Is there any way that I could pass some text through a link from a site that I own to a site that we don't... basically there is a text box on a page that wants the visitor to enter a promotional code.. Well since they would be linking from our site we wanted our promotional code to go in the box when they click the link on our site.. I have tried a few things and nothing works.. I am not even sure it is possible. Here is the site so you can see it

http://accounting.epowerc.net:8181/signup/signup.asp

and our promotional code is MIDW01

Thanks,

Mechanix

Unless their ASP is explicitly looking for a value to be passed through either a GET or POST method, then no, there is nothing that you can do.