This is my first post here, but I'm a regular over at AVS Forum.

For awhile I've had a pair of lamps on a single X10 Lamp Module. I've been using a "Sundowner" wired controller to power them on/off and dim/brighten. Today I received an IR-543 that I planned to use to integrate control of these lamps with my Harmony 520 remote. I've had no problems integrating power-on and power-off of the lights. I am, however, having problems programming functions to dim 100% to 0% and to brighten 0% to 100%.

I've tried programming multiple "dim" and "bright" commands but the progression in either direction choppy, not smooth at all. I've tried every speed/delay setting with no luck. When I hold the "dim" button on the Harmony the progression is smooth as it should be, but when I try to program as part of an activity I can't achieve this same smooth dim and brighten functionality.

Any help? Thanks!

If you have the standard XPD3 switches, you can't do that. You need scene-capable switches. I have the XPD3's & I have to press & hold the dim or bright buttons on my Harmony 659. I think the IR543 is okay, but I'm not sure.
You can use other switches that can have the ramp up time adjusted - see this thread:
[Link: remotecentral.com]
That way, you could press ON & the light would ramp up slowly.
Bill E. in this forum gave me a lot of advice. He runs the smarthome.com website, which will have everything you need.