Midi OX seems to run fine on a 64-bit OS, but apparently due to some registry entries not being seen by 64-bit apps like a Sonar X2 x64, it wouldn't work.
If you could live with running a 32-bit Sonar session, then it seems that this might work fine for you.
Certainly worth a try.
I just ran a test install and running of Midi Ox, and it installs and runs fine, but I do not have an x32 Sonar installed to test things completely.
So, maybe you or someone could give a 32-bit Midi Ox with 32-bit Sonar a try on Win 7/8 x64?
Bob Bone