Cool, now lets set it all up. You should see the FootCTRL at the bottom, if not, that means it's not selected, so just select it if it does not show up. The FootCTRL will be our "Driver" Driver as in, the FootRoll attribute will be "driving" (controlling) all the groups that we made earlier on. So, with that in mind, select FootCTRL and click on "Load Driver" It should now move to the top into the "Driver" window. Now we need to load the appropriate groups into the "Driven" window. So, in the hypershade, select FootRotate and then shift select BallRotate and then click on Load Driven in the Set Driven Key Window. Now the Driven window should have those two groups in there.
Cool. Now we select the FootRoll attribute in the top (Driver window) and then we select both the FootRotate and BallRotate in the bottom (Driven window), you can select both of them by holding down the left mouse button and dragging down. Once both of them are selected, select the rotateX attribute on the right hand side in the Driven window.
Now that we have everything selected, just make sure that the FootRoll attribute is set to 0 in the channel box, if not, set it to 0 and then hit the Key button (found at the bottom of the set driven key window). Now we have set a key for it's default position. After that we select the FootCTRL in the set driven key window and then set the FootRoll attribute to 15 in the channel box. Then we go into the Driven window (bottom window in the Set Driven Key window), and select the BallRotate group. With the group selected, rotate in the X axis to a value of about 40 degrees or so. Then select the FootRotate group (again using the Set Driven Key window for all the selection). Once selected, rotate in the X axis to a value of about 40 degrees or so aswell. These are not the standard values, you can use any value that you want. Once you have adjusted your rotation values to the way you like it, select everything (the groups and their rotateX attributes) in the Set Driven Key window again and hit the Key button. Now you should have a foot roll that is animated from 0 to 15.
Don't worry about the toe lifting at the same time as the heel, we will fix that up in the graph editor a little later on. Now we will set the FootRoll attribute to 0, and in the hypergraph select HeelRotate and shift select ToeRotate, and in the Set Driven Key window click on Load Driven. So, now we have HeelRotate and ToeRotate as the "Driven" this time around.
Make sure that the FootRoll attribute is set to 0, if not then set the value to 0 and then select the HeelRotate and ToeRotate groups and select the rotateX attribute and hit the Key button. We have now set the default value for these groups. Now go to the FootRoll attribute and set the value to -15 and then set the HeelRotate and ToeRotate rotateX values to something like -40 degrees or so, and then select the groups and their rotateX attributes in the Set Driven Key window and hit the Key button again. Now you should have a FootRoll from 0 to -15 now. Pretty cool hey?
Cool! You can now close the Set Driven Key window and play around with your newly created FootRoll attribute. We now have a FootRoll! Yay! We do have one more step and that involves using the graph editor.