I use liquid Dawn or any laundry detergent around the perimeter of the boot to slide the wire along. You have to have 4 pair of hands sometimes to hold one side down
Be sure to put the rubber boot on all the way before sliding the wire on. The part of the wire which has the spring attached should be the last section to go on at the bottom. I usually start at the 7:00 position and work my way clockwise to the 6:00.