No way to do it via software. That said, you could install a switch. It would be quick and easy and only cost a couple of bucks.
To be truthful though, seems like a waste of time and money. The light from the trackball uses almost no money at all in power - especially when compared to the fact that you already indicated you leave your machine on 24 seven (so do I by the way). I have the happ lighted trackball on mine as well and have no issues. The bulb is easy to change and costs 2 bucks or so if it blows. Not enough to go through the hassle in my opinion. Best of luck and cheers.
Ray