(a) Direct to the bike's battery, with an fuse in-line (3 amp will be plenty).
(b) Using the dedicated spur that is hidden away behind the headstock or oil cooler.
(c) Running a supply from anything on the bike that is already powered. For example: The tail light, the front side light, the standard auxiliary socket under the seat.
If doing B - on the newer models the connector is just behind the oil cooler and looks like:
On older bikes the connector is the same but you need to look backwards down the side of the shock below the headstock to find it:
Note it is the lower of the connectors in the photo, the other connector is something to do with the fuel emissions canister thingy that is not needed outside of certain US States
Just done mine 59 1200,using the link that Wapping suggests.
I got my Canbus plug from Nippy Normans £16 delivered.Sorry i don't know how to put the link in.
The dealer i bought my bike from would not sell me the part,but i believe that some dealers will.