You could buy Two 220 VAC timers, which I think are available such as for a hot water heater.
1 Timer = dimmed
2 Timer = full
What might be harder to find is a 220 VAC dimmer. Basically, I would run the output power through the timers (however, they would only time when powered...which is why I would have to leave the ballast on). I don't really like that idea, but it is necessary to run the timers, unless you can find a timers that can run off of seperate power like 120 VAC
I run the power wires the timer power and the line contacts on the timer. One timer would feed into a 220 VAC dimmer to whatever level you desire.
I believe that you have a 4 pin wire off that output right? Or is it a regular cord? All it is a 220VAC circuit with a neutral and a ground and two hot wires I believe.
The wires to your lights would be on teh line side of one timer and the other side of the dimmer switch.
I'm starting to think the trained monkey might be easier...LOL!
But that is probably how I would do it.