I tried it with luxeon 3 watters. I have pure T5 and 12 x 36" bulbs. It takes too many point sources to make it work. I had 24 LEDs at $4 each, and they still could not create a very noticable shimmer. Maybe in a smaller tank.
If you want to do it, you could use a point source light such as a 70W MH bulb (minimal heat/waste). Plasma lighting could do it, but not cost effectively. I'm sure someone has a LED solution for under $300 for a large T5 setup, but it's not cheaper then a single 70W MH or two.