That thread you speak of tells you how to fix a squeeky clutch... so where do you find the shift linkage to fix that squeek
You are correct; the primary topic of that thread is how to fix a squeaky clutch.
The secondary topic is the squeaky shift linkage which is brought up in the responses posted by: Anonymous, Chocolate32, and Quy.
Maybe I'm wrong but I believe they are related but separate issues. To me the squeaky clutch noise sounds like it's coming from inside the engine bay and the squeaky linkage noise sounds like it's coming from underneath the car, that noise is best heard when driving around with the windows down.
When I have time this weekend I'm just going to get a can of white lithium grease, print out the Celica parts diagrams, drive the car up on ramps and track it down and grease whatever is squeaking.