Joe,
The current switchlinc does not support two way in that it doesn't transmit back it's state or "kick" another code based on a state change. However, for most of our applications, the current version does all that we could want.
As an example, you could have a "movie" mode that sends a P-1 X-10 code which would drive the dimmers to given levels. Then, have an "Intermission" mode that would drive the dimmers to different levels.
I hope this answers your questions.

PS. We use an X-10 mini controller ( I guess about $25) to do the programming of the dimmers as it's the easiest device to use for the purpose. You take each dimmer to teh level you want, then send a program code and it "stores" the level in memory for that X-10 code (P-1 for example). Then when a P-1 comes down the powerline, the dimmer goes to the preprogrammed level. Easy really.