old thread, i know.
i've got an epson 4990. loading negs into the carriers is a bit of a pain, but a quick and dirty way to make contact sheets is to first use the 8x10 'film area guide' instead of the carrier. lay your negs down on the glass, emulsion side DOWN. this will reduce the occurance of newtons from the bottom glass. get a piece of 8x10-ish frosted glass, place it frosted-side-down (i.e. in contact with the top of the negs) on top, then close the lid.
preview, select the area, scan at 300 dpi or whatever. works very quickly, and is faster than the darkroom.
this is also how i scan my odd-format negs, like 16mm, 828 and 127, but at higher resolution of course. more dust than if they were in a carrier, but it beats not scanning them at all.