I've wanted to do this for a while and finally got it done. It's an electric hoist mounted in the attic over the garage primarily intended to take off the hardtop. And, who knows, it might be handy for something else. I used the Harbor Freight 440 / 880 lb electric hoist. This has been done and written up a ton of times, so there's only one minor twist here.
First, observations on how it works - great! I doubled the line and use the snatch block not for the extra capacity but more to slow things down and make it easier to control. The top goes up smoothly and settles back onto the tub perfectly. It's easy as pie.
I mounted it with some unistrut I found cheap in a local scrap yard, 2x6's from another construction project, four lag screws, and a PVC flange (that last being the only new thing here). My garage ceiling is framed with 2x12's and since I caught three of 'em with the stacked 2x6's it'll carry the load easily. The flange doesn't look too bad, protects the sheetrock, and goes easy on the wire rope when it does rub. Photos below. Hope this helps someone else out.