What do I need to do to raise a toilet 8-3/4"?

I have a “sunken†utility room whose floor is 8 3/4 inches lower than the rest of the house, and want to raise it to the same level as the other floor. The utility room floor is a concrete slab that has a toilet (the drain pipe is embedded in concrete). How do I do this correctly? I may be able to cut the top of the drain pipe / flange out with a Dremel, but that probaly creates other problems. Any advise is appreciated.

What kind of pipe is it? Cast iron, abs, pvc? Depending on what it is, and the size of the pipe would determine the easiest way to resolve this. Once you have the old flange of, a no-hub connector, or maybe even just a glue-on coupler, a short riser, and the new flange would be all that is required. You'll probably have to chip out around the pipe for a bit to make room for either the coupler (if plastic) or access to tighten a no-hub connector onto the pipe (if CI). Keep in mind that the new flange should be installed on TOP of the finished floor, so however you are raising the floor, leave room around the pipe (if it is 3") for the new flange to slide over the pipe which you can leave long until the finished floor is in. If it is a 4" pipe, you have the option of either an inside mount or outside mount (preferred). Make sure the riser is plumb, or installing the flange and having it level will be impossible.

I would break out the concrete and extend the pipe from there.
There isn't really a good way to extend past a closet flange.