How to map a key to change Buoyancy values?

I am working on a submarine demo and want to be able to change the buoyancy values of the craft in order to dive into the depths. I have found the values in the lua script and can set them manually. However, I want to be able to map a key to do this while in the game. Any ideas how to do this with Flowgraph, Lua or a combination of both?

Found the answer to my question. If you go to entity in the flowgraph node menu there is a set property node. With this you can change those physical values.