Option to use channeling skills as a toggle instead of holding down a button

The title says most of it. For me it hurts my hand to continually hold down a skill (mouse or keyboard). If there was a configurable option that let you use a channeling skill as a toggle i.e. by pressing the button once to make your character keep channeling until you tell them to do something that interrupts it, that would make these skills a lot more appealing to use.