Violins have curved fingerboards, so by changing the angle at which you hold the bow, you can play one string at a time. the curvature on a guitar fretbaord is much smaller, and so you cant do anything like that...and even if you did, the bow would not work nicely on wound strings.

If you want to make that sort of noise (not a bow on a guitar, which sounds horrid, but a violin like guitar sound) get an Ebow (electronic bow) it is a small electronic device that is held in the right/picking hand, the ebow produces a magnetic field, that causes the string to vibrate...its hard to learn to uses it, placing it so that just one string vibrates can be hard, usually it involves muting the other strings, but once you learn how to use one,an Ebow can sound amazing.

www.ebow.com has some great info to get across what I'm talking about