Yes bumper has to come off. Here is how it's done.

1) Remove the front turn signals on the bumper, they are held in buy one screw, undo that and rotate it out.
2) In each wheel well you will see two screws on the part of the bumper that wraps around...remove them, and then you'll have to pull the bumper edge around the mounting bracket there
3) Looking down from above behind each light, you will see a nut threaded onto a bolt coming from the front of the car, rmove that. YOU may want to slide the coolant resovior out of it's mount to get to the passenger side nut more easily
4) Looking into the slots left open by the bumper lights, you will see 2 bolts on each side mounting into the frame, remove them
5) Supporting the bumper slighty pull it off.
6) You can now access the bolts mounting on the lower part of each lamp assembly