Ever done one before?

I spose the first thing to do is pull the head and make sure it really
*is* the gasket.  There's a chance that it could be a crack in the
intake or head (though much less likely).  Even if you pull the head
off and the head gasket is obviously hosed, i would still take the head
down to a local machine shop and have it magnafluxed for cracks and
checked for true-ness.  It's a pretty inexpensive process, IIRC.  If
the head's warped, they can mill it flat.  If the head's cracked, it is
junk.  If the head is warped and you put it back on that way, there's a
good chance that you'll be in the same situation in the near future.

There's a start, anyways.

Basically you have to find out why it was leaking and fix it.

1.  First step would be to disassemble the upper end of the engine.
2.  Next step would be to determine whether the gasket was leaking or
the head was cracked and leaking or the block was cracked and leaking.
3.  Based on what you find in 2 you will have to:  Replace the gasket
and probably mill the head; Replace gasket and the head; Replace the
engine.

My sense is that you have not done this before.  You should consider
having someone with you who has done major repair work, or just pay a
good mechanic.

I would think a compression test would be in order first to make sure it
is a head gasket. If this engine is the 3.1, they had a lot of problems
with intake gaskets leaking.

I would say, at this point, you definitely have a problem either in the
intake gasket or the head gasket/Warped or cracked head. Either way,
you will need to go through the intake to get to the heads. I would get
the intake gaskets and head gaskets. When you pull the intake, look at
the gaskets, you will see where they fail (at either end of the
intake). If you find the intake gasket failed, you could just stop
there and install the redesigned intake gaskets (no special procedure
other than torque sequence, and no special sealer)and probably be good
for another 200k. If you don't find where the intake gasket failed, you
could continue on to the head gaskets. Since you have to remove one to
get to the other you could stop when you find the problem. Again, if it
is the 3.1 liter engine, they are known for intake gasket issues. It is
a fairly easy job with a good set of mechanics tools and some
mechanical knowledge.