The phone was easy with the sony there is a "developer kit" available that contains a program where you choose what keys you want the phones buttons to send to the computer then you create a "skin" for it. I think the site was developer.sonyericcson.com or something like that. It works the same way the desktop and media player remote profiles work that are already included with the phone, you are just making your own.
I got a new phone a couple of months ago (cingular 8525, cingulars version of the HTC Hermes) There are so many possibilities with the new pocket pc's it has me rethinking the entire way my carputer is setup.
To be honest i dont know if stopwatch works on the newest version of cf I have to update it, but have been working on finishing up CFiG first.
Good luck with the rest of your install, try searching for "sony developer kit" on the forums, I think that will turn up what you are looking for with the phone.