Hi "salty",
I recently replaced the timing belt and idler pulleys on my 99 ES300. The pulley bolt is standard, meaning that you would rotate it counter-clockwise to loosen. Fortunately or unfortunately, Lexus uses thread-lock and therefore a great amount of torque is needed to break it free. I'd say somewhere around the 250 lb-ft (spec for this bolt is 159 lb-ft).
To hold the pulley/damper in place, I purchased the following tool from Sjdiscounttools (http://www.SJDiscountTools.com )
Schley Products 64300 SCH64300 1 $61.30
Harmonic Damper Pulley Holding Tool
You will also need a puller to remove the pulley/damper from the crankshaft. I used the two bolts that came with the schley holding tool with a bar type puller since they fit into the threaded holds of the pulley/damper.
Hope this helps. Best of luck!