Take off the 3 bolts from the bottom pipe to the upper cat, then take off the heat shields 4 bolts and remove it (unplug the upper o2 sensor) then undo the 5 nuts on the top of the cat. Make sure you use 6 point sockets to minimize rounding off nuts and bolts. Spray everything well with PB Blaster or another penetrating oil the night before (WD40 isn't really that good for penetrating compared to PB but it's better than nothing).
You will probably need to weld a bung into your exhaust AFTER the 2nd cat otherwise you may get a CEL for bad cat. You will probably need to lengthen the wires of the o2 sensor to reach the new position and plug the old hole with the proper threaded plug. Cleaning out the cat is pretty easy with a hammer and large screwdriver.
When you put it back together, reuse the metal gasket between the cast iron header to the cat, and you may need to get a new gasket from the cat to the down pipe (make sure you have this before you take it apart. I bought copper header flange gaskets and drilled out the holes to get it to fit because AutoZone didn't have the right gasket). Make sure you use anti-seize on all your nuts and bolts.
Let us know if it helps and take pictures and post them of what you find.
Should take about 2 cocktails <img src="/forums/images/graemlins/cheers.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" />

Everet <img src="/forums/images/graemlins/patriot.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" /> <img src="/forums/images/graemlins/kewl.gif" alt="" />