Different Value Steps

Hey guys,
I was wondering if it was possible to change the value of the step that a slider value will step. For example, the X and Y values for a background image.

It would be useful to be able to change (by clicking instead of typing in a new value) these values by steps of 0.1 to 0.001. How is this done? Thanks.

Hold Shift+alt and slide.
Shift alone gives larger movements.

Aha, perfect. Thanks Rich!