Not bad at all to do yourself.  You need to put a spacer between the lower
A-arm and the body of the car, jack up the car, remove the 2 bolts for
the lower balljoint on that side, and pull the driveshaft out of the
inner driver.  The inner driver comes out with a sharp tug (leverage
is your friend).  The seal is right there; screwdriver or special tool
for pulling seals, new one goes in carefully with a non-marring hammer.
Couple hours tops, with nothing more exotic than a ratchet set, prybar,
and non-marring hammer.

By the way, for this question it doesn't matter so much, but it helps
a lot to specify left or right side of the car, rather than driver's side
or passenger's side.  This group is pretty widely geographically
distributed, so it has happened before that assumptions were made and
were wrong on something that mattered.

Dave Hinz