If it had a slider on the side, it was not X10, sounds like a Leviton standard dimmer.

Your basic, parts are fine, but you need to review X10 technology before you do this job. You may end up having to filter for noise and having to add a coupler repeater. We sell to a lot of custom installers and I can't think of any of them that would do a job without a coupler repeater. It just is not worth the risk to you, having to deal with an unreliable system and an unhappy customer. When doing this for money either do it right, or pass on the job.

Review the articles on noise and coupling located here: [Link: act-solutions.com]

Bill
www.homeautomationnet.com