This worked for me too.
I had read that thread where SD said to rename the CatRoot folder to CatRoot3, but did not try it since I had just deleted my stock images using the FutureDial usb to serial cable.
When I saw this post, I figured I'd try it.
I put the usbser.sys file in the C:\WINDOWS\Driver Cache\i386 and in the C:/WINDOWS/system32 (which I have tried before). But this time I first renamed the CatRoot folder to CatRoot3.
After I rebooted, I could access the shared > audio and pics folders with my Moto usb cable!
Very nice ...
Thanks for posting this again ...