First create two routines, one to turn on the lights, and one to turn them off. Then create a simulated switch (which has to be done through the IDE, as far as I can tell.) After that, using the "Switch activates home phrase" smartapp you add the routine to turn on the lights to the "On" and the routine to turn off the lights to the "Off". Then the simulated switch will both turn on and turn off the lights.
It sounds a lot more complicated than it is.One thing I found is that I cannot change a routine once it's been added to a simulated switch, I have to remove and recreate it. A minor thing, but it was pretty frustrating the first time I tried to edit an underlying routine and ended up with the switch not working, even though the routine itself worked.