Hi. I don't know the answer, but did do a Search for the past year and didn't come up with anything.
Here's a
link to the official Universal site's Disability information page. It includes a link to download their Guidebook for Guests with Disabilities. There is also a phone number and an address to contact for more information - it's about 2/3 of the way down the page, in the text.
It does say on their website that due to the "dramatic motion" of their rides, none of the ridew will accomidate an
ecv or a power wheelchair. I know long, long ago, when we were there, a theater show with 3D and motion, called something like "The Magic of Hanna Barbara" did have a portion of the theater that did not move. Other rides that held a manual wheelchair were ride cars and the whole car shook or moved, plus it moved in space from one place to another. So, I don't see how they could make a non-motion run of the ride (although someone else may know something I don't).
At WDW,
Star Tours and
Body Wars can be ridden in a non-motion mode, by requesting it from a CM (during a non-busy time). In those rides, the theater is relatively small and totally closed during the show. The whole theater is the simulator, so it's not hard to isolate the movement while using the other parts of the show. As far as I know, none of the rides at Universal are that same sort of format.