I'm not sure if this will work, but if it does allow the array, use $userfile_name and so on.
If that doesn't work, I'm guessing PHP won't do multiple file uploads simultaneously - something I never thought about. One of my current projects processes up to 10 simultanous uploads, but uses Perl (and does *not* use any libraries for upload processing
The PHP idea *might* work, but I'm not sure - you should be able to process the uploads manually as you would in Perl (bypassing the built-in method) but explaining how to do so would take a while (took me a long time and lots of trial/error to figure it out in Perl).
Hope this helps.