Roy:
Before I replaced the liner, it was different. As for modifying an existing liner, as opposed to replacing it, the one trick of the trade I can offer is that the best way I've found to cut the foam used for liners is with an electric carving knife. You can usually pick up one at a Longs, K-Mart, Target, or similar store for around $20, or for $1 at a garage sale. It works surprising well on the foam.
Bill, tgo
(Message edited by lbpesq on December 30, 2008)