Its a very easy job mate, You need to remove the crank pulley and gently ease out the crank seal with out damaging the thin metal washer behind it, Once you've done that its just a matter of tapping the new seal in gently.
Use a small screw driver to remove the seal, But as I said make sure you don't damage the thin metal washer behind, Not unless you've bought a new one spare.
I've done the job a couple of times myself so good luck with it fella.
Rob
