I cut up some rubber fuel line for use as spacers. The o.d. is 9/16"; i.d. is 5/16". Sturdy stuff!
I cut it into 2" pieces, and used them to hold the spring in place. They fit very snug, and worked great! I used 6-7 total. (I understand the kit only comes with 3). I then used a small screwdriver to pry the spacers back out.
I replaced this boot the first time with ease.
P.S. I used vaseline. Boot practically put itself on!