If your meter looks like a spinning disk, you're out of luck—for now.
I have read where a fellow used an LED and a photodetector to watch his spinning disc and measure how long it takes to go around. Sadly I can't find the web page anymore. Still, it is possible.
The BlueLine PowerCost monitor (same as the Black and Decker version) both have sensors that, in addition to reading digital meters, can read the black line on the analog meters. There's no reason that WattVision couldn't do exactly the same thing. It's primitive, to be sure, but it works.
I have read where a fellow used an LED and a photodetector to watch his spinning disc and measure how long it takes to go around. Sadly I can't find the web page anymore. Still, it is possible.