I've been out of the loop for a while but Im wondering if this is possible inside iclone.
Mirror or flip an animation from left to right so as to turn the opposite direction or perform all right hand animation with the left hand and vice versa.

There is an option in the timeline.  Right click on the animation in the timeline and select "Mirror Clip".

Is this a new feature to iClone 8? I do not see the option in iClone 7.
To be clear, I am referring to mirroring a motion clip, not motion layer.

yes this is a new feature for IC8.  See it here at 1:44
https://www.youtube.com/watch?v=EgTseTVPcmY

You can flip animations in blender fairly easily but when imported into 3Dx, it has bizarre results. does anyone know how to set up the export from Blender to use flipped animations in 3Dx?

There is nothing special with Blender export. Once you use Ctrl+M and X, simply export as FBX.
But in 3DX after importing use attached profile to apply symmetrical bones assignment swap.

Here is a quick workflow: