Ck out the growlogs for similar techniques. A small 150w hps would be ideal, but you may have to make it slightly taller to fit that light and there will be heat issues, so a small PC fan or something similar to move the air around and bring in fresh air will be needed...a box that small will have to have good ventilation or the plant will use up all available co2 very quickly...no co2=no growth. Ck these out...

Look here: Closet / Cabinet Growing - Cannabis Forums Message Boards - Medical Marijuana, Cannabis Club, Dispensary, News

And here: Grow Log - Cannabis Forums Message Boards - Medical Marijuana, Cannabis Club, Dispensary, News