Might need to have a rear-eject, or some kind of vented piston configuration to let the ejection charge out and still keep the rocket together. Then, make sure the rocket is balanced in a horizontal configuration with the spent engine. With slightly slanted fins, they will act like a waterwheel and introduce a spin. Not canted fins like for a spin on ascent, but slightly slanted in the same direction like at 80-deg instead of 90-deg to the body. When the rocket is falling horizontally the slanted fins will have a drag-bias to introduce a spin. Because of the extra fin drag on that end, might need to balance the rocket slightly nose-up? Could need some trial and error with the balance, not sure how easy you can do a ground "glide" test of that before a flight test.
I have seen a rocket descend that way by accident when the shock cord fails and the chute goes along with the nose. That would be pretty cool for a long rocket like the Mean Machine.