Obviously before trainees can stack and de-stack they need to be able to use the hydraulic controls safely. This is done in the same way as the lesson for a counterbalanced machine.
Nearly always there is one lever for raise/lower/tilt and a separate lever for extending the telescopic boom as shown in this picture.
Note the large lever in the picture. On this machine there is a small switch on the underside of it that can't be seen in this picture but is described on the next but one slide.