I got it to dual mine last night, I was stuck in the back and forth of sha256 / scrypt as well. Before using zadig to overwrite the driver my com port was 4 then it disappears as stated above. I changed the com port to 1 it the batch file for cpuminer and it fired up, very slowly mind you. Once it started hashing scrypt I launched cgminer and it went to work also. I did drop the clock speed for both. I am only using one miner mind you. Currently I am only getting 250 KH/s and 8.77 GH/s

I am sure this is of no/little help but that is what I did messing around and it worked.