You might have a very hard time with that one. The best thing I could say is LED Blinky I know works with u360s, but not in a functional way that could remotely stand a chance in working with a gpwiz, or any other encoder for that matter. Hyperspin relies heavily (entirely) on LED Blinky to re-program stuff on the fly, which is why I mention this.
How does MAME handle the 49-ways? Does mame support them as "analogue" joysticks?
Also, on GGG, it's listed that there's software to change them. While I doubt hyperspin can handle it, maybe there's other options? Maybe hyperlaunch configurations?
Also there's button combinations you could try implementing with the gpwiz49's, aren't there?