I've found that -- not surprisingly -- using a standard servo with LEGO parts is annoyingly troublesome. The mounting holes and case size don't match up neatly with LEGO hole/stud spacing.
I can imagine making an adapter part or two, perhaps as easily as drilling appropriate holes in a piece of plastic. But I'm wondering if anyone else has already come up with a clever solution to this problem. A quick Google search turned up only one item, using a nonstandard (smaller) servo.
Any pointers appreciated!