I have used the specimen holder with holes drilled in it full of gravel inside the tank successfully. I prefer cutting the head off as described, cutting it into fourths, using bridal veil-like stuff to strap them onto the rocks I have selected so that I can choose where I want them. The bridal veil was available in a convenient $2.99 roll about 5 inches wide at Wal-Mart in the crafts section. You don't have to have high light, but you do need moderate water flow or they will melt.
I have a 20-gallon long and a 10-gallon tank side-by side longways under a pair of 48" NO 40 watt Super Actinics and a single 40- watt Actinic White. I am running Skilters on both tanks and using them for propagation only. I have found that I can put the Skilter on the 20-gallon all the way on one end of the tank, leaving one end with low circulation. I sometimes just cut off mushrooms and toss them in the low-circulation side where they find some gravel and grab it within about a week or two. Then, I move them into the current to make sure they are gripping tightly before I glue them where I want them in one of my other tanks.
I have about 5 colors I like to mix on the veil-rocks. You can make some interesting "Rainbow rocks" this way.
As long as you keep water moving at least a little, you can pretty much just hack these babies up mercilessly. The only way I have been able to kill them was in a bowl of gravel that was outside the tank. This will quickly become a bowl of mushroom soup. The people that reccomended a gravel bowl must have meant to put the bowl in the bottom of a tank.
They are quite hardy and adaptive. The stem you cut the head off grows back too, sometimes into more than one if you are careful to be sloppy with the cuts!
Have fun.