How do you reset a Maintenance Required light on a 1992 Dodge Caravan?

The local dealer here (Tucson) charges $43.00 for this procedure. The van requires this at 60,000, 90,000 & 120,000 miles for a total cost of $129.00... not including your time and travel. I wish I could find an alternate method, but it appears it's not something that you can do yourself... even using something like, say, a "scan tool". If I ever find a better (read