Make a verizon iphone 4 able to work for sprint?

I'm trying to sell my iPhone and its a Verizon phone and the girl that wants it has sprint can I jail break it? How? Websites will help and how to do so will also thanks

Verizon iphone 4 was designed to run only on the verizon network

No.

While Verizon and Sprint both use CDMA Verizon will not activate a Sprint device and vice versa.