Hard Boil Eggs in a Microwave

When talking to a friend of mine, she told me about a little holder she has, to put eggs in, that will hard boil them in the microwave (without the shell, of course).
My friend said you have to watch the time very carefully, because even w/o a shell, they WILL explode if you don't. And you MUST pierce the yolk.
I googled, and this is what I found (because I don't have one of those gadgets):

"This is an excellent way to prepare eggs for salads, etc. You won’t have to peel them either! Several eggs may be done at once, but they need to be rotated to cook evenly. Eggs take 45 seconds - 1 1/2 minutes per egg. A shorter time per egg is required when cooking several eggs. The reason for this is explained in "Dealing with Multiples" in Definitive Microwave Cookery II.

1 egg
nonstick cooking spray

Lightly spray small custard cup or other small microwave container. Crack egg into container. Piece egg yolk gently. Cover and cook on Medium power (50%) for 45 seconds -1 1/2 minutes. Check egg after 45 seconds, and finish cooking at 15 second intervals until egg is solid. Let stand and cool before slicing or chopping."

-Susan-