Just finished taking my closet room down today. It can be done, and you'd be suprised how easily. I had 8 gorgeous loves under a 600 hps w/ equalizer-air cooled w/ a 6in can-fan (240 cfm) and another can-fan (same size) connected to an oversized carbon filter to compensate for the added resistance. The fan exhausted the air in the closet in just over a minute which created a fantastic vacccum effect. I cut one huge hole in the top left of the closet and exhausted all the air into the walls using a Y-connector (the wall being exhausted into was shared with my bedroom closet...may re-think it if its shared with a neighbor). I also cut two rectangle holes at the bottom either side of the door as intake vents *cover with vents, you don't want bugs or trash entering your room. Add a heat-shield to your hood to reduce heat and you'll be gravy. I also ran CO2 but thats another story.
Anyways, after the rambling, in essence it can be done. Make sure there is NO light that escapes the cracks of the door (dead give-away). If so, keep the hallway light on when people come over if necessary. Also, ONA Gel is your best friend when it comes to apartments. Put a little in a cup and place it in random hidden spots (right before your grow room, at the front door, AC Vents, etc). Well, my 2 cents, happy growing.
O and just like the guy above me stated, install a lock. It doesn't have to be a pad lock, but a new lock so only you and MAYBE another person have.