This is probably a little late, but I'm actually flowering right now with CFLs. Everybody told me it would be a waste of time, but it was all I could afford to do since these plants were basically forced upon me by one of my friends. I couldn't just leave them like that.... I saw the lil look in their... nevermind.
So anyway I have four 42W CFLs that produce like 2700 Lumens each, giving me 10,800. I am quickly learning that this is probably only enough light to flower one plant so i will probably end up adding 2-3 more to it. You have to make sure that the entire plant gets blasted with light. With CFLs, you have less heat and you can put them at least an inch or two away from the plant. Check on them peridically and if you see the tips of the leaves starting to turn to a lighter color and curl up, then i'd back it off just a tad bit.
Right now i'm going to experiment by putting each pot into its own milk crate and attaching the CFLs to the sides with one hanging over the top so that each side is illuminated properly. If the entire plant isn't being lit it won't grow equally, you'll know because some parts will look like they're developing faster than other parts (i.e. big top vs. small bottom). If you have a plant growing straight up with one main cola, then its a lot easier. One of my plants one main cola with two big branches shooting out making it wider. Harder to light that whole plant. The other one has one main cola. That one is a lot easier to manage and light.
If I had the money to get a light i'd probably do that, but until then this is what i'm working with and it seems to be working so far. I'm going into my third week of flowering and its coming along. Hindu Kush