How to use 4 prong 220 generator out let with a 3 prong 220 device?

Depending on the device you can usually find a new wiring harness. I recently changed my stove from a 3 prong to a 4 prong by simple unscrewing a couple of screws in the back and putting on a 4 prong wiring kit. Took me a toal of 10 minutes and I am by no means an electrical savant. Go to Home Depot and just a new wiring harness for under 20.00 dollars. Hope that helps.