At the risk of coming off like a jerk (which I've done before, thanks) I was wondering, in a more philosophical sense, what this data would be used for, anyway? Is the number of lines of code changed really a good matrix for anything? I was asked to provide total lines of code counts, over time, for some projects once and the managers quickly realized that the data didn't really tell them anything. They eventually became more interested in the quality of the code (code reviews), how long it took to fix particular defects, whether or not code had to be re-written, etc.

That being said, a decent (I'm only halfway decent) shell scripter (unix or cygwin) could whip up a short script to parse 'p4 changes' into 'p4 describe', grep the pertinent results to a file, then use the built-in 'wc' command to count the lines. It shouldn't be that complicated, as perforce does most of the work (through describe') for you.

-Matt