Hi Willy, This can be done, however will require considerable work. Hopefully you have PVC plumbing, which will make the job easier. After pulling the toilet, and disconnecting the water line, you will need to remove the existing "closet flange" that the toilet is bolted to. If PVC, this can be done with an inside pipe cutter which is an abrasive wheel attached to a drill. You also will need to gain access to the outside of the pipe to enable you to install a coupling to connect a new 6" piece of waste pipe. If the floor is concrete, this will require breaking up the slab around the flange. The new piece of pipe will terminate at a new closet flange at the correct height and should be screwed to the platform you plan to place the toilet on. Then you can add a new wax ring, replace the toilet and install a longer water line from the shutoff valve. Now, if your piping is cast iron, again you will need to remove the closet flange with an inside cutter, and install a "Fernco" coupling, which is a rubber collar with compression clamps that mate iron to plastic piping. you would finish as described above. Good Luck.