Thanks Démian.
I finally added Bridge support. You just have to run the blue Bridge button from the shelf and Megascans assets will transfer over. Make sure Command Port is enabled from the preferences. Meshes that are saved as FBX won't cross over though(their materials will). If there was an easy way to convert these I would like to add that functionality.
I also added a script to add Surfaces to an existing mix. Handy if you forgot to put snow/dirt on one or more items. All selectors except displacement will be reused because that one is unique per surface.
** Edit **
I found a bug with the Bridge application. If you transfer multiple items you will get multiple imports of the same item. The cause is the with the Bridge application. I had a chat with one of the Megascans devs and they will fix this in a upcoming version. For now just import one item per time.