Tony,
If you can remember I bought a set of genuine Lexus manuals at JAE for the GS 300 secondhand. They are excelent books, at the last meet we used the instruction to check the SAT/Nav diagnostics on Rod's GS.
I have purchased an electonic copy on CD from ebay in America, however these are very poor quality and show very little.
If you can buy some they are well worth the money :)