The crank seal is a metal ring with a rubber seal around the inside of it. If you are reusing the old timing chain cover, you will need to knock the old seal out, and put a new one in. You can use a pipe the same size as the seal, and rest the cover on two 2x4s and whack it out using the pipe and hammer.
Once you have it out, clean up the cover, and then set the seal on - it is a tight press fit seal - a rubber mallet is not enough to get it on - I used short length of a 2x4 on top of the seal and hit it gently with a hammer so as not to damage the seal as you hammer it in. It takes a fair amount of force to knock it in. Make sure you put it the right way in (I would have to go look at mine to remember which side you put it in from - I think the flange of the seal is on the outside of the cover).
Once the seal is on the cover, test fit it, to make sure everything lines up okay - there is quite a bit of movement of the cover before the bolts are tight, so you can move it around quite a bit to make sure the seal is perfectly centered around the crank.
Once you are happy with that, then take some engine oil and lube the part of the seal that contacts the crank - you do not want a dry seal on start up or it may burn it up. What I do then, is put a thin layer or RTV on the timing cover, put the gasket on, put a thin layer on the block mating surface, and put the cover on. I use two bolts that do not go through the water pump to hold it in place and make sure it is centered. Then get the water pump - I usually already have the backing plate and its gasket in place. Do the same thing with it - apply rtv, gasket and then RTV again, and put on the water pump. Place a couple of water pump bolts in place and then double check how the timing cover is sitting relative to the crank - needs to be perfectly centered. Also check how the timing cover is sitting relative to the block - it may not be quite flush - that's okay so long as the seal is centered over the crank - RTV will take care of the timing cover/block issue when you put on the pan.
HTH