First off, I am pretty much just a beginner, but:
The problem I see is trying to cover all the angles. 3 small plants would do OK, arranged in a triangle with the lights overhead. But what about when they grow up? You've got to get the sides and the bottom, and it will get worse and worse. The plants will still grow, but only the top will have leaves.
That is a pretty high wattage CFL though. Maybe it would work if you have excellent reflective surfaces all around...but I doubt it.
I was in a similar situation with 4 plants and not enough light. I had to let the runt die rather than making them all suffer. Then I still only had adequate light on 2 of the plants. Luckily they turned out to be the females, and the neglected third was male.
I suggest you get several smaller lights, like a 6 of the 100 Watt (really 26 Watt) bulbs. This would run you about $40 from Walmart. You could buy the lamp parts with the double sockets for probably $10-15.
Or, you could get some florescent tubes. I like these for the bottom because they are cooler and burn the leaves less. They can lay right up against them. Get a double row of tubes (maybe two 3' to fit a row of 3 plants, or a triangle of three 2' to fit a triangle) to cover the front and back of your plants, use the smaller CFLs for the mid range, and the high powered for the top.
Lastly, before you go adding a bunch of little CFLs all around, really think about what you're going to hold them with, and how easy they will be to adjust...To me, this turned out to be a huge challenge. I am starting to think that the double sockets actually make things harder...