My Halogen is 300w, and had a two step dimmer (3-way) switch. One switch position turns it 50% on, the next 100%. I simply leave the switch in 100% mode and am using an X-10 dimmable lamp module with it. The lamp module is rated for 300 watts. Works fine.

Do NOT use a 300w lamp module if your halogen is greater than 300w. Do NOT use a lamp module if your halogen uses a infinitely variable dimmer.

Dave