Similar to position, select the object with the material you would like to animate, open up the material information and type in the units you would like, or click and move the mouse on the text next to the parameter. In this example, use the first offset parameter (not the second) to 0. Move the header in the timeline to your next keyframe location and then adjust the parameter as needed. If you want the texture to loop seamlessly the parameter needs to be a factor of 1 (so 22, 5, 10 will also have a loop if need be). I use higher numbers if I am trying to loop a number of textures at different speeds for example (one material loops at one where another is at 4 which would be 4 times faster).