I could teach your pup to free stack in about 2 days.
They love to learn this!
You know how to bait a dog, so get your bait and stand in front of him and walk into him to back him up a couple of steps. Do this slowly. The moment his rear feet come close to being where you might want them, not perfect, but close, mark and treat. You can make with YES, or THERE, or a clicker, or anything you like.
Once you get his rear feet there, and you have marked and treated, work toward him standing there and not moving rear feet. Use the bait gradually to work his head where you want it, at the same time moving his front feet a little.
You work this is small bits, a little at a time. The first step to set is him backing his hind feet into where you want them, and the not moving them when you step out away from him.
Once you get that, then using bait to turn and move his head, you can teach him to stack the front.
This is easily faded to small signals, such as I toe touch in front of me to get a dog to stand. Rocking a hip towards him gets him to step back and position his back feet, and the small hand motions with the bait or my body gets him to fix the front feet for the rest of the stack.
The one really important thing to remember is this is taught in 2 sections. First you teach him to position and set the rear feet, and not to move them, and then you teach him about the front feet.
If your pup is as smart as I figure he is, he should have this down PAT in a week or so.