Max's plugin already supports custom folders-- and IIRC, you can put them wherever you like.

FWIW, I don't think MoI's suppport of asset management is "one of the most important aspects of our workflow." In fact, I almost never use it unless it's for Kitbashing, which is a very niche effort.

I recommend trying OnShape or other full engineering CAD package if you're looking for asset management. MoI's stated intent is for artists, not engineers.