I have found that installing the Bluetooth keyboard stuff fixes nearly all of the issues with USB keyboard.

It is my understanding that it includes xmodmap.

Reference my article on the USB Keyboard dock I built.

http://linuxslate.com/N770DockingStation.html

With the keyboard I used for the above, I still have a minor keybounce, or key repeat problem, but it is 100% useable.

When my 770 is in the dock, and the dock is on, the on-screen keyboard does not pop up when you tap in a text field, and the enter key works as it should.

When I turn off the dock (i.e. disconnect the USB keyboard), the 770 works as normal.

All I did to get it to work like this is to install the Bluetooth keyboard package.