Modifying "File" extension

I’m trying to modify the “File” extension in the Control Panel so that a web blog entry could act as a photogallery. Actually it already does… what I’m doing is customizing it for a client so that it will auto-generate custom folders and file names based on a drop-down menu and date field. I’ve got the extension setup with my new commands though I’m having trouble figuring out the syntax for getting the drop-down and date form fields via post inside the extension file.

Any help would be appreciated.

Thanks.