I know this post was from 2011 but just in case someone else comes across it, what I’ve found is that premiere does not allow for Keyframe on Text Tracking. There are plugins which will allow for this such as BorisFX and using After Effects is the other option.
Great. Another post that’s first on Google’s SERPS, yet instead of answering the question, the OP was told to go post it somewhere else. Very helpful guys. Thanks. Guess I’ll keep searching somewhere else…