seals are fairly straightforward to replace. If you don't have a good manual, first step is to get one, they usually have great instructions and pictures. look, or take a picture, so you know which side faces out ("V" of seal faces inward) and how deep they go in. Most important part is to not bend or warp the seal as you install it. I do a couple things, 1 is I always buy 3, murphys law says if you just get 2 you'll mess up one of them (and it can always be returned, I just keep it on the shelf for emergency's) and I figure if I have to replace the seal, I replace the bearings as well since it's apart anyhow.
Also, check your vent hose for kinks or dirt/bug plugging. The most common cause of a seal blowing is as it gets hot from driving, the vent is clogged and the pressure goes past the rubber, taking oil with it. Did you get the brakes hot, or was the diff low on oil?
I did the rears on mine, and tried the aftermarket seals. I had a problem with the little spring around the inside of the rubber popping off, finally went to the dealer and got the OEM seals, they looked better made than the part store ones, and went in with no trouble.