Sorry to hear of your problem but the Lexus standard settings have been proven to be incorrect. Here in the UK we had the same problems with inner tyre wear on the IS 200 & 300 until one of the LOC UK members who happens to be a geometry specialist, worked out the correct settings for the car. Believe me, not only have the revised settings recovered the geometry and stopped the undue and uneven tire wear, but the car drives a whole lot better as a result.
If you want the new settings please contact Tony at http://www.wheels-inmotion.co.uk/forum and I'm sure he'll pm them to you. Hundreds of first generation UK IS models have been reset, so it's been totally proven. However, Lexus have not learnt the lesson and the second generation IS is known to suffer from the same problem. Unfortunately the later model only has toe adjustment so recovery is not so easy.
Yeah I can vouch for Tony's geometry settings on my 2003 IS300. My first set of tires wore out on the insides but when I went to Wheels In Motion and had a new set of tires and the new (at the time experimental) geometry proposed by Tony back in 2004 the car's handling was transformed. Since then I have been back to Wheels in Motion for regular checkups and the handling of the car is more precise and the inside wear problem has been taken care of.
