Matt,
If i understand it right, my subtitle prep tool can do this.
It can output FCP compliant XML, and comes with a very decent text generator (that is free, btw...)
download a trial from
http://www.videotoolshed.com/?page=products&pID=12
Perhaps you need a little aid of Spherico when it gets in thefinal stage.
Contact me direct if you like to discuss any custom work you might want to have done. You can reach me at bouke@videotoolshed.com
(i can think of a few options to streamline the entire process)
Bouke
www.videoToolShed.com
smart tools for video pro's