A/C Retrofit?

I'm hoping some of you resourceful RIU folks can help me out here. Last winter I successfully grew a single plant in a closet under a 150hps. Unfortunately the only reason I managed to keep the temps within the safe range was that it was winter in New England. This winter I'm upping the lights to a 400w switchable. I use a small closet near a window in a spare room, and if temps got crazy last year I just popped the window open for a bit. Obviously the 400w will need much more aggressive temp control. I have a couple of older window a/c units, and I have considered using my 6" inline fan to suck in the cool air from one of these at the nearby window, but this seems inefficient and rather conspicuous. Also, I suppose, for that matter, in the winter I could just pipe in cold air through the window. In any case I'm wondering what other solutions you people have come up with for similar problems. Possibly gutting one of the a/c units and retrofitting it to work inside my closet? Is this possible or even safe? My closet is surprisingly tall so there is room up top for equipment. Thank you in advance.

P.S.- I am comfortable and competent with basic electrical and plumbing work, so I'm open to radical ideas here.

You could go to lowes and find a floor register or 2 that fits the outlet on your unit duck to the close. and put in an exhaust fan near your lights. Should give good air exchange and keep cool.