According to this website
http://www.nolico.com/saveenergy/dimmable_lamps.htm
you don't need any kind of special dimmer, they're designed to work with ordinary incandescent dimmers.
"Our Dimmable Compact Fluorescent Light Bulbs are compatible with most standard timer, motion detector, photocell sensor, and dimming circuits. With these bulbs, there is no need to purchase expensive "Fluorescent Compatible" timers, motion detectors, photocell sensors or dimmers. These will work with products which indicate that they are for incandescent only. They have a dimming range from 100% to 20% with no flicker or hum! The wait is over for high quality dimmable CFLs, and we have them at the best price!"