Sorry to ask a stupid newbie question, but . . . where is the 06-07 GS forum?
FYI, my 07 GS350 RWD oil filter canister cover looks like it has an end cap that can be unscrewed but it is actually part of the cover and not removable. I just removed the cover carefully and drained the oil out of it slowly to avoid spilling or splashing.
On a different Lexus community site there is a very detailed thread with pics from a guy changing the oil in his 07 GS350 AWD. In the AWD model the oil filter canister cover is tilted down and there is a plug or a cap that can be removed to pre-drain the oil (by sticking that little plastic thingy in) before removing the cover.