One-handed gaming?

[superluser]

Hey, I'm really enjoying the Penumbra games, but there's one thing that really bothers me. I don't have fine motor control in my left hand, so whenever there's a puzzle involving things like turning (using the mouse) and running (using the keyboard), it becomes nearly impossible. I have to turn myself, take my hand off of the mouse, put it onto the keyboard, run a bit, take my hand off the keyboard, put it on the mouse, turn, take my hand off the mouse...

Alternately, I can hold down one key with my left hand, but that would preclude running or even pausing from walking.

Years ago, I learned how to do this pretty well in Wolfenstein all on the keyboard. Unfortunately, Penumbra doesn't let you assign the turn function to the keyboard. Has anyone thought about this sort of situation and worked out ways of dealing with it?