All right, this shouldn't be too difficult, first of all consider a candle and it's flame, besides moving the intensity also varies. Both of these things can be animated, you can use a noise controller for this but you might as well animate it with keyframes by hand, just turn on auto key and move the omni a bit, move to another frame and move again, you get the idea, then you can use the .. to view the resulting curve and also animate the intensity parameter of the omni, it might take some trial and error to get it right, good luck!
Ideas.. use your imagination, or google, or try some tutorials.