Don't attempt to fit without removing the bumper... it's a nightmare.
Far easier taking the 10 minutes to remove the bumper, disconnecting the fogs and pulling it away so you have room... prise the old off... pop the new one on and refit the bumper - nice and simple.
I'd say it would take you an hour max to take your time and do it properly... takes two seconds to disconnect the fogs... the horn is in the engine bay, does not need to be removed.