I don't know if this is even possible. In the attached code snippet, what I want is that when the user changes the value of the <SELECT> element (onChange?), the VALUE part of the param element needs to be modified so that the value of <SELECT> goes after the "variable=".
So if the user highlights the 2nd <SELECT> option, the param would read (upon being submitted):
<param name="uploadURL" value="http://www.url.com/page.asp?variable=2
<param name="uploadURL" value="http://www.url.com/page.asp?variable=">