My position with a springer is the same as with a pcp. My right arm goes around the outside of my right knee and the heel of the stock rests against my right thigh. I have moderately high cheek pressure which locks the gun at the rear; head/gun/leg all in contact. At the front my left arm wraps around my left knee and the gun rests on the uppermost part of my left arm. It is not held at all at the front. You could easily use the back half of this stance and shoot off the knee; this is more-or-less what John Costello does.
For me it's dead steady, I cannot remember missing a sitter for wobble: it's so steady you don't really need a conventional trigger technique as there is no hold pattern to time for.