Just thinking for fun here:
(I don't know the exact process, but here's the concept anyway.) Build an ultralight kit. Something like a Quicksilver - or whatever, basically the cheapest flying tricycle design you can find. Quicksilver advertises their Sport MX can be built in 30-40 hours. But plan to register it as an experimental, amateur-built (so it has an N-number and the time can count as airplane time).
As you build it, add another engine. Does this need to be a "normal" engine? I have no idea. Can it be an electric motor with a little propeller, like a drone motor/propeller, that provides no useful thrust? Just attach it any old place, on a wing strut or something. Would this count as a "multiengine" airplane? Fly it around burning <3 gph gaining lots of "multiengine" time but absolutely zero useful multiengine experience.
Have I discovered the ultimate loophole here?I want someone to show up at their airline interview with 1500 hours of multiengine Quicksilver time and let us know how it goes.
Using that logic, you can fly a C150 wearing some sort of motorized propeller beanie and log it as MEL