The 2476S can be programmed with an X10 Primary Address.
It should be X10 compatible. Others here have them in their setups.
One difference is when you turn it on or off with the local paddles. It will send an X10 on or off back onto the power lines. On the address it is programmed to. So it is a two way module that X10 seems to have never implemented.
With a power line transmitter it will absorb some of the power line signals. That usually does not effect things that much.
The 2476D dimmer was not a completely compatible module. Smarthome used a different X10 protocol for dimming and brightening. %DIM that X10 controllers like a CM15A and Active Home Pro didn't do. The older On 100% then dim down did work.
If the label is still on the front plate. It will give you the date code and hardware revision.
Depending on the revision. I know 6.0 and above. Have an Air Gap switch on the set button. By pulling it out you can disconnect it from the power line. So you can test with out having to remove it from the wall. But be careful. When you push it back in. Don't go all the way past its normal position. That would factory rest it and the Primary X10 address would be erased.
The earlier revisions don't have the Air Gap switch so to test with it out of the installation. You have to remove it from the wall.