What size is the transparency window in the lid? You can scan anything up to that size, theoretically. I was not able to look up that model on Epson's support site, where I expected to find the specifications. The 4870 has a 6"x9" window, which would easily take up to a 5x7 neg.
See this post--this is how I do it:
http://nelsonfoto.com/v/showthread.php?p=124805#post124805