Getting an existing rigged character into the A.R.T. pipeline

I have a character that was already rigged, animated, etc. before Unreal 4 came out. Is there any way to get this guy into the A.R.T. pipeline smoothly without losing any of the work? I know this has been asked before here, but just curious if anyone had found any other less hacky workarounds since the question was posted.

Would love to leverage some of the Unreal A.R.T. tools (adding custom bones to existing hierarchy through A.R.T. interface, anim interface, be able to have my character show up in “edit existing character” and “add character for animation”, etc.) but I don’t want to re-rig my guy from scratch and lose work.