Is it possible to pass a querystring when creating a new document in a sharepoint list?

Question

I would like to pass a querystring to Infopath when creating a new document (based off of a content type that I created and published with infopath). Like so: http://server.com/Forms/Form1.xsn?String=value I know that Infopath can handle querystrings but I'm unclear on the process behind creating a new list item from content type. Is there an .aspx page that Sharepoint calls? We are using WSS3.0

Thanks in advance!