2003.02.28 21:14 "RE: Photoshop tiff limits", by Belshan, James
I've seen ImageMagick recommended as a workaround. They used it to split the files up into Photoshop-sized chunks. They didn't say whether they could put them back together again. Maybe you could open up multiple Photoshopsm at the same time, with all of the pieces, so that you could see the effects of your touchups on the whole image at once.