I wanted to post about customizing mentioned a few pages back. I figured I'd wait till I had some pics for reference.
As for how to get the Imaginext guys apart, I do use the boil method. I never seem to get the 'pop' however. I've boiled 25th G.I.Joes and they've come apart pretty easily, Imaginext don't work with me as well. But it's still my best option.
The secret is really letting the hot water soften and or melt the glue holding the back and front body pieces together. Without that glue/joined plastic being softened and loose you will not get these guys apart in a useable way.
The following was my first attempt to disassemble a figure:
The pegs inside the body cracked. The glue/plastic never softened and the plastic just gave way when working it apart. The legs, arms and head were ok, but I needed the body too, so this attempt was a failure.
This was my next try, and it went better, and is useable, but not perfect. The parts all came apart okay, but one of the pegs snapped and stayed lodged in the body. With at least 1 peg still okay, I was still able to get the finished figure back together again. Even with both pegs broken you can still seal the body together with glue, however it's better and stronger to glue the pegs back into the peg holes.
My third try was perfect, all limbs came away fine and the body had two undamaged pegs, but this was Aquaman, and I only needed the head this time. It would of course figure that when I didn't need the body it would come out undamaged.
Now I use the same method for the girls as I do the guys, but it's even harder.Because the space in the girls bodies is smaller and more compact, the glued areas are closer and there's less space to work it apart.
You can see that the limbs came apart fine, but the body isn't really usable without a lot of sanding and repair. I had taken a Catwoman apart and she came out perfect, but Harley was another story. Thankfully I didn't need the body from the figure.
Overall, use a double boiler to heat your figure. I even place a rag at the bottom of the pot containing the figure to keep it from touching the metal pot. Then boil, boil and boil a little more, and test the figure throughout. Don't tug the joints too much as they are a softer plastic than the body. Use a blade/X-acto to loose the body but try not to cut the body. It's a delicate line to walk, and be sure to not apply any real pressure. And of course wear safety gloves and even goggles. No cut or injury is worth it. It works about 50/50, but with Imaginext, you ALWAYS have extras of something, so if the 1st try is a failure, try again.