the procedure is covered in the factory workshop manual for the 2000
civic.  i seriously recommend you track that down and use it as its the
most comprehensive description of what to do.  i replaced the outer cv
joint on a driveshaft recently and have some pics.  i'll try to dig them
up over the weekend and post them.

in summary though, you use a slide hammer to pull the cv joint off the
outer end of the shaft, replace the boot, then replace the joint.  but
there's a circlip ring you need to be very careful of.  the joint is a
pig to get back on because of it, and if this is the factory driveshaft
and the boot has been replaced before, it may not have been reassembled
right rendering it impossible to get the cv joint off again and you'll
need to buy a new one.  [it's possible to slide the cv joint past the
ring on reassembly.  if this happens, the ring opens too wide past the
end of the splines in the joint and the joint cannot be forced back past
it again.]

if the cv joint is damaged, [makes a clacking noise as you turn] it's
too late for that joint and it needs to be replaced.  you can buy just
the outer joint from honda, but it's not cheap.  cheaper than a whole
honda shaft though.

for after-market shafts, they're usually not maintainable - the cv
joints are permanently fixed.  but the boot outlasts the joint for those
things, so it's not a problem!

when faced with boot replacement, most people simply replace the whole
shaft as it's cheap [<$100 for the whole thing] and quick to replace
[<20 minutes].  after-market shafts are ok, but the quality is never as
good as the honda units.  provided the boots aren't allowed to split and
the cv joint loose lube, get grit contaminated and subsequently wear,
factory honda shafts will last the life of the vehicle.  ask tegger.
[www.tegger.com]