I also have a 97 LX450 (actually its my wifes). I've had two Cruisers before this LX though. The AC compressor is fixed (mounted solid). the belt for the AC compressor has an idler pulley that is adjustable. you'll need to remove the front skid plate (4 12mm bolts) that's right above the front steering damper/shock. once removed, just loosen the bolt on the front of the idler, and then loosen the long adjuster bolt until the belt can be removed.
the alt/fan belts are a little tricker, as the alternator adjusting mechinism is hard to get to. what i have done is remove the 3 bolts holding the power steering fluid resovoir and i can get my hand down in there.
hope this helps, todd
ps (on two occasions i replaced what i thought were "noisy" belts. when i put it all back together the new ones were just as loud. i ended up buying genuine toyota belts, and they too were loud. ultimately it was the small idler pulley (bad bearings) for the alt/fan belts. it doesn't seem to do too much, it doesn't change the direction or increase pressure on the belts/pulleys, i have 100K miles without one.
