That axle seal is pressed in. I pressed mine in myself but I had the whole transmission apart when I did it. I think you could do it with it still on the car by prying the old one out and gently tapping the new one in with a big socket and hammer. I am not sure on that so get someone else's opinion on that.
You can get the seal here as part of a kit. I'm not sure if they would sell it individually so you would have to contact them.
http://supercar-engineering.com/sc2/...be682217ba4bd0