Just use some 75 watt fluro tubes and move them around so that the light hits different parts of your plants.....moving the tubes as you see fit.

I once built a grow cab for a medpatient with a 250w HPS and 2 75watt Fluros. Yielded 3 1/2 OZs from one plant without any special training.

I use HPS along with fluro tubes to grow my fruit/vegtables. Works like a charm.