X-10 is neither... it's X-10. The most common way of controlling X-10 is via an RF remote, which sends a signal to a RF to X-10 transcever that plugs in the wall (X-10 signals are sent through your house's electrical system). You can also buy [a] IR to X-10 converter which you can use with a standard universal remote (such as the Pronto or SL-9000).

I'm sure Robert can answer the question better. :-)