What you want is the switched live from the fuse box.
Now mines a Gen1 but chances are the fuse box is the same or similar.
If it is, it's just a matter of popping one of the switched lives out and soldering on to the spare tab.
The trick is locating the little tabs that hold the live tab or conductor in.
All the photos were on the old forum, but that cannae be accessed any more.
See if I can get the photos in here;
Pop the fuses out (noting where they all go!)
Now look for the plastic clips;
Ease the clip back (an instrument or jeweller's screwer driver should be ideal) and push one of the switched lives out.
Solder on your live feed, remembering to fit an inline fuse (you want it as near to the fuse box as poss)
Bob's yer Uncle;
Hope that is of some help.