Anyone remember Jack Stone? I do, but only because I was intrigued with the new hairpieces at the time. Moreso, as a customizer I wanted to see if they were compatible with minifig heads.......so I admit I bought a few sets and tinkered around. You can see one of the hairpieces on a BF miniquin here:

With Toy Story 3 coming out LEGO has released some nifty sets featuring larger-than-life minifigs sporting newly-molded hats. Again, I wondered how compatible these hats are with standard minfigs.
The Woody, Jessie & Pete figs are molded with a 4mm-wide cavity in the top of their head. Their hats, respectively; are molded with a 4mm peg that fits down into their head. The hats are secured into the head using adhesive. Let the fun begin.
I used the traditional boil-n-pop method to remove the hats from the heads. This involves filling up a stainless steel kitchen pot with water and setting it on the stove to boil. I drop the head/hat in right away and never cover the pot with a lid. When you see bubbles forming you can extract the piece with tongs, then using gloves or dishtowels pull the hat off the head. It comes off fairly easy but the peg part will of course look a bit mangled.

I cut off the peg flush to where it meets the bottom, inside of the hat. Just the hat itself remains and does not fit a standard minifig head. Next, use epoxy putty to fill in the hat.

Immediately moisten the top of a minfig head and press the hat onto the head. Because of the moisture the minifig head shouldn't pull bits of the epoxy out. Rather, it should leave a 5mm depression. You may have to fit and adjust the epoxy a few times before you get a nice, secure fit. Trim the excess epoxy then smooth out the edges using your finger or sculpting tool. Let it dry for 2 hrs.

Nothing left to do since the 'mess' is located on the under/inside of the hat.

-A