For a crank seal replacement, it's as straight forward as they come - what I would suggest, is that you turn the engine to TDC and line up the cam & crank timing marks before removing the belt & pulley, it makes it a little easier to retime when reassembling.
Also, when last was that timing belt replaced? Given the labor involved it might be worth your while to replace both cam & crank seals, the water pump, the timing belt & tensioner pulley.