this might just be the most usefull website ive ever signed up for haha, so if he wants it to bud it will need a door?
Haha, you got that right.
Yes, to initiate flowering, you need to put the plant on a 12/12 schedule, which means 12 hours of total, uninterrupted darkness per day. You will also airflow during the dark period, which means extraction. At a basic level, a PC fan at the top will do the job for a box that size, and some holes at the bottom for intake of fresh air. The intake holes and the extraction point will have to be made in such a way that light can't enter.
Be aware that plants usually stretch 2 to 3 times theirsize when you flower them, and if you grow from seed, the plant will need to grow for a while before it is mature enough to flower.
It will be a challenge to flower in a box that small, but it can be done. You will probably need to employ some form of training to keep the plant small enough. Check the GrowFAQ at the top of the page for some info on this.