What kind of grind does it have? Is it one of the one side grinds? If so, try to move it around in the clamp and the various angles until you can get as close to the factory bevel as possible. Then only sharpen that side until you feel a hair edge on it, then get a piece of leather strop, or some cardboard note pad backing, and strop the flat side until the hair edge is gone.
If it's got a regular double ground blade, just pick whatever angle is closest to the factory one and sharpen it like any other knife.
