I've been using my dad's old incandescent studio lights (Smith-Victor) but decided to buy some CFL lights instead so it's not so hot under the lights. I got some cheap Fovitec ones from Amazon (supposedly 105W though I doubt it) and they seem to work just fine, but I was previously using TRIAC dimmers and these obviously don't support dimming.

I'm using both shoot-through and reflector umbrellas for a few different lighting setups. I don't know if these old lights can take something like a theatre gel but the CFLs stick out past the edge of the fixture anyways. How can I dim these, either in steps (25%, 50%, 75% etc.) or continuously (like a dimmer)?