I haven't done this myself, so keep this in mind. I have changed out all of my other speakers however. My front door speakers had to have the opening grinded down a bit to fit the speaker into the door. Also, not to forget, the drilling that had to be done for the mounting holes.
I came across this thread that will be helpful.
http://ptenthusiasts.org/forum/showthread.php?t=39927
They are 1" tweeters in a 3.5" housing.
Looking from my dash tweeters... I couldn't say much about the depth since I don't know the actual depth of the factory stock speakers.
But there will definately have to be some mod done to get it to fit in the stock housing area (holesaw/dremel?).
If anyone has a parts list with a picture, it could be roughly determined on the depth of the tweeter. I don't think you should have a problem with the depth of the speaker though.