Getting pilots to use their feet isn't that difficult. Most training aircraft mask adverse yaw rather well if you fly like a sissy, and if you use little aileron (ie move the yoke about 10-20° from neutral) it's quite hard to pick up on.
I simply show them by looking out front, rolling to around 30° AoB to the left and then right and using your feet with aileron, in order to stop the nose moving the opposite way as you roll. Practice left/right continuously while keeping the nose on a point, and the airplane should react like its on rails and just roll side to side without turning. To actually turn, you roll in the same way, with coordinated rudder, neutralise everything once you're at the AoB you want, and fly the turn with neutral aileron and rudder (there's no aileron input, so no adverse yaw). When you GET TO THE POINT/HEADING you want, you roll out co-ordinated on that point. None of this 10° early crap letting adverse yaw finish your turn off.
While climbing, you hold a bit of (usually right) rudder to keep coordinated. This can be seen by looking out front again. In a left climbing turn, you release a bit of the right rudder as you roll in, then reapply it once in the turn to counteract the left turning tendencies again. I don't make a huge point of looking at a stupid little ball, when you can get a better feel by looking out of the window and feeling whether you are sliding side to side in your seat. Then you get a nice warm feeling when you're students fly nice and coordinated, and they keep the ball in the middle without even looking at it.
The problem lies with people knowing they need to use rudder, but not what to do with it... So they just hold some rudder in the direction of a turn and think they are proper stick and rudder types as they slide around the sky holding opposite aileron to stop the over-banking they are causing themselves. Amateurs!