Hi,
you can't fake mouse movement, in the sense that if you read the mouse position, that's it, there is no other way.
the best way is to compose mouse movemement and custom inputs, then if the user has a mouse it works, if the user has a joysticks it works.
this is how you do it as well if you want to support mouse and touch, the best way is to accept both inputs.
Bye,
Jean