I want to make a series of text titles zoom out and then stretch in the middle as they reach full size like a rubber band having over stretched and then pinging back into place in CS4. I have looked through the text animation presets and can't find anything there so looks like I need to build the effect from scratch.
Need to know what are the basic steps I need to take to manipulate text in this way?
This is fairly easy to do with an expression. Dan Ebbberts has a couple of examples that would work. The first is explained in the "It's a Fact Jack" part of this page. You would apply the expression to the X scale property. Just change the y to an x then write the final line [x, 100]
If that doesn't do it for you try looking at Dan's Elastic Connection page. You could tie the x scale of the text to a null then animate the null's position to get your elastic effect.
The most direct option is to just animate the X scale by hand. It may take you a few tries to get the exact look you want.