I just bought my 3G xoom yesterday and the Motorola Camera connection Kit. (micro to standard cable) It is $20. I am using a microsoft wireless mouse. (comes with a mini usb bluetooth plug.
the mouse works great. My only issue is that I cannot get the on screen keyboard to worrk but my bluetooth keyboard works fine with the mouse.
Why did you buy the host cable if you have a bluetooth mouse and keyboard? The Xoom already has bluetooth.