You will need an IR to X10 converter such as the IR543.
I use the IR543 with my Harmony 880 and am very happy with both.

Unfortunately Logitech is screwing with their Web based software and pissing off a lot of us that spent many hours setting up our remotes just the way we wanted them. Now if you update anything on your remote you can loose some of the functionality you used to have. I used to love my Harmony but now I am deathly afraid to update anything for fear of ending up with a paperweight.
Check out the Harmony Remote section of this forum before you buy. They are nice remotes and work well with lots of different A/V and X10 equipment.
Unfortunately I would not longer recommend them due to their recent screwups.
I would now be in favor of a remote that uses locally installed programming software so that you are in control of when you upgrade.