Yes you setup a keybind for the toggle (in the KC interface, i dont recall where).

Other things of note: your camera view is important. If your mage isnt looking at the same place as your main, the blizzard could end up weird. Will have to play with it.

Also, last time I used this, KC basically PiP switched to each screen to broadcast the mouse click so there was a bit of a delay in using the ability and actually being able to control your people. It may or may not be like that anymore.