I can't find an article directly for fixing the trackpad on the unibody, but basically follow the guides here. All you need to do is remove the battery and hard drive, and you can see the trackpad right there. There are 8 very very small screws that hold it in place. Just disconnect the cable from the logic board and slide it out.
Now, I'm a little lost after re-reading the thread. People seem to be talking about a 13" MacBook, when it looks like the OP is talking about a 13" MBP. **Just looked up the part number from her post, and found one on eBay. Matches it perfectly from what I can tell. Having to do the same thing on mine, except mine is screwed up from beer.