Since I had to replace these two filters, this weekend, I decided to document what I did for those who haven't done this before and want to save some money by doing it themselves.
So, take a look and tell me if anything is unclear; I'll do my best to make it better.
Here's the link:
http://www.conceptualpolymer.com//Documents/Lexusfilterchange.pdf
Update: 3/6/2011: Optional cabin and air intake filters:
Cabin (Panel) filter: Wix 24883 $14.99
Intake filter: Wix 49185 $16.77
Both available at www.amazon.com
Dave