Cool. This is exactly what I want to do.

I made a patch cable to go from the intercom directly into my sony
camcorder; it is a simple resistor divider level matcher. I mounted the
camera on a tripod and bungeed the tripod down in the back of the 152 I
trained in. I crank it up to the roof and it gives a great view, and the
audio is excellent. It takes just a few seconds to install and remove too.