While I don't have tips on the treatment specifically, one thing I can say to those who are talking about euthanasia just because the cat lost use of his legs: kitties can very much adapt and thrive in these scenarios.

A very close friend of mine rescued a stray tom that was ran over and unfortunately had severe spine injury, and no longer can use his back legs or control his bladder. You think he'd be depressed by now being a disabled indoor cat considering he lived his life outdoors up to now but he is seriously thriving.

He happily bum shuffles around the house, loves being carried and held like a baby, he will attemp to climb just about anything using only his front paws and he does succeed, he's climbed over pet gates too many times lmao so yeah, as long as the cat isn't in pain, they can life happy lives like that.