I would first remove at least 1/2 the water.Make sure that you have some freshly mixed up water also.
Then take the live rock out and put that in a plastic bins or buckets.
Lay some newspaper over it and soak it down good with the water you removed.If the water will cover the rock I wouldn't even bother with the newspaper.I would then drain out some more water to place the fish in.I would leave just enough water to keep the substrate slightly submerged.If you can move the tank without disturbing the substrate,that would be ideal.If not you can scoop it into a bucket,then you can either rinse it with tankwater later.Some say to start with a new sand bed to help avoid nasties that will get stirred up from the move.
One tip,work slow and move stuff out of the way when you have removed it from the tank.It's so easy to step on something or trip on cords.
Good luck.
