This is derived from the 2005 Legacy workshop manual so you can replace "trunk" with "boot"
License Plate Light Assembly
A: REMOVAL
1. SEDAN MODEL
1) Remove the trunk lid garnish by removing the 2 bolts behind your number plate.
2)Remove the trunk lid trim by removing the trim clips (12) and stopper rubbers(2) and remove the trunk lid trim.
3) Turn and remove the bulb socket. Disengage the clips for the license plate light assembly that will now be visible, and remove the license plate light assembly.
Good luck