In my case, I made sure I opened the clamps around the boots as much as possible AND oriented them so that I could reach them easily from underneath the airbox. I had the two on the left pointing out the left side of the bike, underneath the airbox, same on the two on right.
Basically I muscled it on after that...kinda working it left and right once it got started until fully seated. It's not something you can do gently, you have to muscle it.