Trying to square up to increase her arsenal, extra mph would be a bonus. You're right, would be pretty tough to teach. A few things to think about when pitching. LOLI assume you are looking for more velocity and feel that squaring up the spin axis to straight top spin will help. There are several ways in which bullet spin might be faster. We know what IR means, you have the upper arm and the forearm. If the two limbs are aligned on the same axis (elbow locked) then the rotation of the upper arm provides no advantage. If the elbow is bent/flexed and the forearm is off axis when the upper arm rotates there is some force multiplication and an increase in velocity. This is pretty much what we label IR. For a bullet spin release to generate additional velocity something else has to happen. One possibility is that the forearm and the wrist/hand have a little IR action on their own. The forearm can also rotate. We don't generally think of the forearm rotating, instead we call it wrist pronation, but it is the forearm. If the ball is off axis when the forearm pronates you have some force multiplication, just like the IR action of the upper arm-forearm. This adds velocity, the wrist may be cupped a little or flat, but the ball must be off the spin axis of forearm.
The other possibility is that as the hand/ball comes into the release the palm faces 3rd base and at release the hand/wrist goes from a position of radial deviation to one of ulnar deviation. To understand radial to ulnar deviation think of the wrist action you use when you hammer a nail. A bullet spin fastball might have either of these actions or a combination of them. It will take some good high speed photography to figure it out and some ingenuity to teach it.