You might try the program Karl has been working on-
ftp://ftp.netcom.com/pub/ka/karl/GEL.EXE. Depending on what format your
sequences are in.... txt, fasta, (?) this program will do single, double or
multiple digestions....
There are "plasmid" digestion programs out there.... check EBI
(http://www.EBI.ac.uk) software section....
If this is not enough, email me...
harold berninghausen