is there a way to Adding extra axes to the input manager programmaticly?
I don’t think so. You might be able to set up a number of “placeholder” axes which have no built-in meaning, and then change how your program interprets those axes at runtime.
Check out the script reference to see every documented function that you can call on the input system.
i realise this a bit late, but i’ll reply anyway for people that have the same problem in the future.
Check out : http://forum.unity3d.com/threads/130730-cInput-2.0-Unitys-custom-inputmanager-got-improved-!
This might just be what you need.