It has been a few years since I have done any Basic Stamp stuff with LCDs but I remember a company called Scott Edwards Electronics (
http://www.seetron.com) that sells serial LCDs made to work with Basic Stamps. They sell a "LCD Serial Backpack® Interface for Alphanumeric LCDs" (
http://www.seetron.com/bpk000_1.htm) that I think may be just what you are looking for.