I am trying to wire in a GFCI outlet from a 3 way switch. There is a good ground nearby but no neutral. Can it be done and how?
It is usually impossible to hang any other load off a 3-way switch circuit. Those wires do not perform the functions that you need. There is no way to --
-- Oh, wait. Smart switches.
Smart switches typically call for changing the functions of wiring in a 3-way circuit. They make it so always-hot and neutral are available at all switch locations (since the wired smart switches need power to function). A useful side-effect of that is that always-hot and neutral are now present for other loads.
We cannot advise further what your options would be, because you have given us very little information about the wiring in your circuit. Every 3-way switch circuit is different.