Did your device enumerate? The device needs to be enumerated by the PC before you can update the driver software, otherwise you'll get an error message similar to the one you describe.
That being said, I wasn't able to get version 3.1 of Freescale's USB stack to enumerate properly. However, I was able to get version 3.0 to work with a custom .inf file under Windows 7 x64. Freescale's USB CDC implementation is standard so you can use the built-in Windows driver and create your own .inf file to load it.
This sounds a lot harder than it actually is. Follow the instructions here, and you'll be able to create a custom .inf in under a minute. Here's the default Vendor ID and Product ID line from v3.0 to get you started:
%FreescaleCDC%=DriverInstall, USB\VID_2504&PID_0300
Good luck!