First off you'll need a darkhouse, a spear, a decoy, and a means of cutting a large spearing hole and removing the block of ice.
To cut a spearing hole you can use an auger, a chain saw, or a special ice cutting saw. Of these three I prefer an ice saw, then an auger. I have never had good luck cutting a spearing hole w/ a chain saw. Everytime I've tried I end up soaking wet and when it's been real cold (20-30 below zero) the throttle freezes up on the chain saw and I've had to let it thaw out in the pickup. I know some people use them, but from my experience, I leave the chain saw at home.
When I use an auger, I drill a series of holes like so:
OOOOO
O O
OOOOO
I then use spud bar to chip the ice between the holes so the sides are smooth and pull the block of ice out w/ a set of tongs. The draw back to using a auger is the amount of slush in the hole after it is cut. To remedy this, I took a small scoop shovel and drilled a bunch of holes in it so it is like a large skimmer.
With an ice saw you get very little slush and it cuts through the ice really fast. I chip a hole with a spud bar to get started then use the saw to cut the hole. If the Ice is over 18"-20" thick, I cut the block in half to make it easier to remove. The only draw back to a saw is it does take a little longer to cut the hole, but there is very little slush to clean out and it makes a nice smooth cut.
I use a set of ice tongs to remove the ice block from the hole.
I look for water about 8-10' deep for my spearing setup. If it's between a weed bed and a drop off that's even better.
Now set up your darkhouse over the hole and take a look down the "Norwegian T.V.".
Have your spear line untangled and your spear ready before you drop in your decoy (learned that the hard way, lol). I like a spear that is 6' long and 9"-12" wide with nice sized barbs and 1/4" to 5/16" tines that are 8"-10" long.
Now drop in your decoy and be ready, but also patient. I prefer the classic white bodied/ red headed decoys about 9" long. Duey's Decoys are some really nice affordable ones. Bear Creek are also good and affordable. I usually place my decoy about 5'-7' below the ice. If the water is murky drop a few egg shells down the hole to help illuminate it. If a pike comes at the decoy, I try to maneuver the decoy so i can get a good shot by just dropping the spear on the pike, right behind the gills.
Well that about covers it, hope this helps.
Here's a real good website w/ some more pointers:
http://wiktel.net/fishspearing/images/darkhouse.pdf
