Tape for protection
Tape vertically as well to protect during bending
Draw notch using pliers as guide
Cut sides with snips
Fold tab into base
Move pliers to outside and continue to bend tab into lamp as far as possible.
File cut edges. They can cut cord cover.
File corners too.
Tape cord up out of the way so it will not restrict mounting.
Further tape cord inside of base to keep out of way. Complete.