I often use alternate controllers such as the Saitek Pro Gamer Command Unit that allow me to program mouse clicks and take the strain off my already tore up trigger finger(s).
I notice that not all games support this. Eschalon is one of them. Book 1 in particular would benefit from this support since the mouse is the only means of movement. It was remedied in Book 2 by the inclusion of the movement hotkeys.
Any chance support can be added for Book 1?