I think it's very possible. BUT you will need alot of devotion- of your time and wallet. So here's my thoughts.
You could buy a frame of a gun that is macro line less and it must be a flat frame top that way it will screw into the gun body. Like maybe a gt frame or something. Then mill some holes into the frame to make it have the same screw hole lineup as the frame. The axe frame im assuming would work because the relay asa regulates air and theres no board to be placed in the frame. But you would need to work with all the board stuff if you get any other frame than an axe.
Here's where it gets messy- and expensive. You need to get a new reg, one that doesn't use macro line, like a gt reg, or a bob long reg. but I believe this would be unnecessary if you used an axe frame, therefore you cause just need a comfortable reg to fit.
Next you mil the inside of the body to we're the air will have a "tunnel" if you will, for it to travel to the reg. Then you need to mill the inside of the body to where the air will go from being regulated to the proper fps to the bolt. Now if you got the Axe frame the air would already be regulated in the asa so you could mill up the air transfer tube and the regulated air transfer tube together. Then get a reg and just mod it so you can screw it on, but the internals would be usless.
So here is my thought. It will be a very very cool thing, so you do this mod to it, send the bolt to pooty, then get a better feedneck, and barrel and it would be amazing. BUT after all the trouble you might as well just buy a MVP pump. Though the resell price on this thing would be around 800 ish if you got a nice anno.