Hello,
As long as you can align the border of the cel
on the scaner bed, it's quite easy. Just scan
the differant part of the cel and then align
them manualy in any picture editing program.

The only things to remember are :

1) Don't change the scanner setting between two
   scans. Especialy, don't touch anything to the
   contrast, brightness, saturation, color maps
   and such.

2) Always scan an over-laping area (1 inch is
   enough). Color near the edge of the scanner
   bed aren't the same as at the center.

   Then cut part of the over-laping area before
   puting together the various parts. So there
   won't be a color differance between the two
   parts caused by the edge of the scaning area.

Cheers,
Yann Stettler