I stumbled upon this topic, and thought I'd give it a try. I created a patch based on an acoustic patch I found somewhere in the Customtone section. Guitar on Input 1, Mic on Input 2, each going into their own signal chain (compressor, EQ, reverb, disabled AMP).
That seems to be working reasonably well. I put a short video on Youtube that you can check out right here (USB direct recording). You can find the patch HERE.