you can surely use a small cfl bulb set up outside of your grow space for sexing clones, especially if you're only going to be tossing the clones after sexing them..
i only have a small closet grow, but i have this small glass shelf in the room that i use for clones and seedlings with a couple of w/e watt cfl's that i have laying around, and it works great.. i simply start seeds or clones under the cfls, and veg them for a few weeks till i think they are ready to go under the 400 watt hps /mh, and i couldn't be more happy..
i only use this small hood that i picked up from the local petsmart store that houses two cfls in it for around $20 or so, and it works great... i just took a piece of cardboard and cut it down to size to help block the light from the shelf so that it stays pretty dark, and run their off times at night so that i don't really have to worry about them being completely dark at night..