I have one cel that is very oversized.
It's 2ft x 3ft!
I think I scaned it in 6 sections and than put it 
back together using Photoshop.
It's not really had to put back together and 
doesn't take that long

If you want to see what the reconstructed scan 
looks like go to:

http://www.sysak.com/animecels/Cel_Index/El_Hazard
/El_Hazard_7_Groucho_Very_Overs/el_hazard_7_grouch
o_very_overs.html

Sorry for the long URL, but I use a description 
of the cel in the cels' name as well as the cels' 
web page.

Regards-
Walt