I used the procedure on the website with pics by Mattias also. More helpful than the Haynes manual in this case, IMO.
http://bellsouthpwp.net/m/a/mattiaso/WebPages/Auto/diy.htm
Main difference was I removed the bracket holding three connectors including the one for the coolant temp sensor for better access. Removing either or both bracket and air delivery pipe will help. A grabber tool with a magnet comes in handy for dropped bolts, so does a strong light.
Replacement procedure, from my notes:
Using a Mighty Vac pump (Sears, $12), drained coolant overflow tank. Then disconnected upper radiator hose at the radiator, and drained/recovered about one gallon from the radiator.
Disconnected small diameter TB coolant hose next to thermostat housing and bracket holding three electrical connectors above thermostat for better access.
Removed thermostat bracket held by two 10mm bolts and then housing held by two 12 mm bolts.
Removed thermostat and cleaned deposits from housing and thermostat seat using solvent and a wire brush (most difficult part of the job).
Thermostat housing had voids on the machined face, apparently repaired at the factory with some type of black filler material. Made cleaning more difficult. Traces of old seal were not easy to remove. Old hose clamp on the TB hose was more stubborn than the housing bolts.
Also replaced temp sensor located next to thermostat with a new one. Not much room for a wrench. Had to use a 19-mm crowfoot and ratchet. Some kind of open socket like on the O2 sensor would work best here, especially because of the pre-coated threads on the sensor, but I could not find one in 19-mm size.
Cleaned all hardware and reinstalled in reverse order:
New 89 degree thermostat with new rubber seal, vent facing top
Thermostat housing (22 lb-ft torque per Haynes)
Housing bracket
Connector bracket above housing
Small coolant hose
Upper radiator hose
Refilled about 90% with drained coolant and some fresh 50/50 mix
Ran engine about 10 minutes and verified temp gauge at 9 o'clock
Alowed engine to cool and topped off to fill line on overflow tank
References:
Conn. bracket bolts (2)
hex M8-125, captive washer, 25mm shaft, 5mm lead
13mm flat wrench, no access for a socket
Thermostat bracket bolts (2)
hex M6-100 (?), 16 mm shaft with no lead
10mm socket, short ratchet
Thermostat housing bolts (2)
hex M8-125, 30mm shaft, 5mm shoulder, no lead
12mm socket, short ratchet, 22lb torque
Temperature sensor
19mm brass body, coated thread, wire and connector attached
19mm crowfoot wrench, 3/8 drive ratchet
connector snaps into bracket from below
Upper radiator hose, 32-44 mm clamp (new)
Throttle body coolant hose, 13-20mm clamp (used old one)
flat blade driver or 6, 7mm sockets on clamps