FYI, was playing with this a bit today with a cheep BT mouse available from Meritline. The mouse would pair with any sequence, but then wouldn't work in the display. The fix was to add an entry in /etc/bluetoothd/hid.conf that specifically disables authentication and encryption. After that it worked well. Not bad for a $10 mouse (which only paid $6 for).

One thing on Meritline: They take forever to ship, so expect a week or two delay to most places...