In marmoset next to the map options there is a channel drop down. I don't know specifically how to do it in UE4, but this model wouldn't work in UE4 as it doesn't use the metalness workflow. I am sure if you ask around the technical talk someone can tell you how to use separate channels in UE4.
Unfortunately, I don't think it's possible to make UE4 match the other shaders by any reasonable means. I think marmoset has a UE4 shader, but it's wildly inaccurate anyway. But to get it to look good inside UE4, I think you need to reduce the contrast in the roughness map. Bring everything closer to a middle range.
I will edit the new form I made for 801 to UE4 (I use it for modular things) and fire it off to you, tomorrow probably. It's easy as pie (pun intended) :D PS working on a new modo to UE4 grid form as the power of 2 grid in UE4 could be a thing of the past in the future (no idea why but there it is).
After a while of troubleshooting, I found this option in the import settings in UE4: It was turned off. And when its turned off, UE4 does some random garbage on the imported collision.
Froyok thanks for the good advice, definitely going to rescale my meshes to fit the new UE4. Is there a playable character I can pull from UE4 into maya for scale reference?
I pretty much was satisfied with the amount of geometry I was able to conjure before starting to low poly and get things into UE4. Below are a few iterations of the cockpit area in UE4
Here is my introduction to UE4 and learning to build a level. I have no experience with environment art so that was a first as well, but I have to say UE4 is massively fun and pretty.
I recently started dabbling with UE4 only to find out they don't have a good lighting solution for grass and foliage, which explains why Epic didn't recreate the UDK jungle level for UE4 :P I haven't tried his technique yet but this thread seems to have some good solutions for nice grass in UE4.