Dynamically Set Value For A File Input Box In A WebBrowser Page?

I'm creating a program that ought to automatically populate a form on a web site with information, and then submit that form. I've done this kind of thing a lot before, but this time I'm running into an interesting problem -- the "input type=file" element.

With the "input type=file" element, a filename box is automatically created along with a Browse button. Clicking the filename box opens the file browser -- you can't type in the filename box manually.

For my program, however, I want to manually set the value of this filename box. Usually, I would just get the element from the page, then call: element.SetAttribute("value",myNewValue). However, with the "input type=file" element, that hasn't worked, presumably because the user cannot normally manually edit the value of the box (though I could be wrong about that being why).[code]...

I've asked this elsewhere once, and one reply was about how I shouldn't be attempting to write a server that will accomplish this anyway -- so let me make sure it's perfectly clear, I'm just writing a client program that ought to mimic what I would be doing anyway. Its purpose is that there's a particular site that I submit things to whose interface only supports one submission at a time, and I have several hundred things I need to submit.