How to relaibly pair a bluetooth device?

I am trying to connect a Wii Board to a Linux (RPi and Ubuntu) so that it is available to the system whenever I switch it on with the button.

The current information about this is quite scattered and not complete. The work done by Stavros Korokithakis (here) and Matt Cutts (here) is excellent but assumes a lot about the systems.

I managed, by pure miracle, to use Matt's wiibal-weighdemo.py once to report a weight (the result made sense) but never managed to do it another time. This is also because I was erratically hopping between various tools and ultimately do not know how I managed to have this running. At least the hardware is OK as I see the Wii Board when doing a hcitool scan.

My question is therefore: what are in 2015 the steps to pair (ideally via the command line) a Bluetooth Wii Board in a persistent way so that switching the device on makes it available to the system?

My goal is to write a Python program which would monitor the availability of the Wii Board, make a weight measurement and expose the result in a reusable format (API and push).