Any words of advice for boot swapping?

I finally got around to doing some hair dryer heat and pops that I wanted to do for some time and while the simple stuff flew by, the boot swap I wanted to do refused to co-operate. The knee and ankle pins were soft, but I couldn't pop the boot out and while for the swap I want to do, it's fine to do the swap at the knees, I'm concerned about tearing the knee pegs rather then popping them.