I've done it on a 7-speed mountain bike. SRAM shifters, Shimano Derailleurs, Cranks, and Cassette.

If you're talking about using SRAM Rival/Force/Red shifters on a road bike with Shimano Derailleurs - it won't work. You need the Shifters and Derailleurs to be all SRAM. Cranks and cassettes don't matter between the two.