Foot/leg rigging sliders

The next thing ive pretty much worked out this week is how to rig my characters foot. The Rigging guide i have from last year shows how to make a bone set up for a foot that can roll forward on the ball of its foot, but this year that set up doesn't have enough points/bones to work perfectly with my character. So i had to find a way around the problem, initially i was going to have a go at just altering the xpresso set up to do the same thing with an extra joint in there, which i think is possibly but would be time consuming, so instead i decided to try to make a separate slider which will sit in the foot controller next to the foot roll slider to make it easy to animate. The extra slider will rotate the upper section of my character foot, because at the minute, the normal foot roll moves both sections of the foot at the same time and by the same amount. By having this extra slider, both segments of the foot will move at the same time, but the upper section needs to rotate slightly more to look right. Ive tested to see if this will work and had no problems getting it to work, i just added a user data to the object that would be the controller, and i set up a range mapper in expresso and told it i wanted it to affect the foot segment and set up with direction he foot should rotate in.