Controlling animation progress with input

To put it straight forward, I am trying to find a way to use direct input, from keyboard or mouse, to control some animations. for my game I require not just to press a button and that the full animation plays, but I want for example by keeping a key down or by moving the mouse in 1 direction to get further in an animation and another key or direction to get back in it. does anyone know wether this is possible or not (and how)?

thanks anyways
tijs