I have started going thro my pile of 'Interaction' magazines (AfME) to try and find what and when members were told about PACE (I don't remember ever hearing about it). I should add that I stopped being a member of AfME about 9 years ago and had not followed anything in the ME world until I joined PR a couple of years ago.
Anyway, I found one paragraph from May 2004:
"......Meanwhile, researchers are busy preparing the MRC-funded trials PACE and FINE."
Followed by a short description of FINE, and a link to the mrc website.
Then in Aug 2004 this:
I never thought about it before, but by calling it PACE was a deception in itself as members who didn't look into the detail could easily have assumed it was about pacing.