I'm sorry, I messed up everything. I meant moving the hero in the X\Z plane. the monkey has sliders in custom\monkey\male\position, when you hold the slider with the left key, the hero moves. the idea is that when you hold the middle key + move the mouse left to right, back and forth the hero walked some distance. rotation is allowed when you hold the right + left key + move the mouse to the right to the left. another thought, hold the right key + turn the mouse wheel and select the tools that are on 1234. I apologize for the misunderstandingsI'm not entirely sure what you are asking for. If it's driving the locomotion so the players moves along the path the character is looking (essentially equivalent of pressing 'forward' with the middle mouse), it should be doable.
How difficult is hard to know without looking further. The game input layer is a mess and it took me quite a while to make the fly camera movement work properly. It also assumes unity has proper support for middle buttons (or any remapped input controls). I will add it to the wish list, but I do not plan to implement this.
As for Monkey in general, I'm waiting to see regular updates from the dev with a clear plan moving forward before I commit on further development and support.
-T-