I have been getting my GoPro video attached to a vbo file export using the information in this thread: http://www.racechrono.com/forum/#/discussion/1153/external-video-for-circuit-tools-vbo-files
Now that i have that working, I thought it would be nice if additional channels could be added for calculated fields. For example, I've run across this information on calculating a faux braking force channel: https://www.dropbox.com/s/xrqmanqldg8up0p/brake-trace.pdf?dl=0
Taking the concepts from the video attaching, I simply added a "braking" column in the headers and stuffed it with data in Excel, then copied back to the vbo file. Wouldn't you know it, but it worked!