Let's say the other node is named Player and is a child of the Root node, also the variable you want to get from the other node is named PlayerVariable the code would be something like this:
var myVariable;
Player PlayerNode = GetNode("/root/Player") as Player;
myVariable = PlayerNode.PlayerVariable;
Not the best example but I guess it's understandable.
That's the way I do it and it works for me, don't know if it's the best way though.
