Unfortunately all UPB switches require neutrals. So does Insteon. I think at this time your only option maybe be some of the Zwave stuff but I don't know about compatibilty with the Omni. Some of the older x10 stuff may work too.
I believe you can use
Leviton DHC stuff but don't think is compatible with the Omni.
Some options may be to use software like HomeSeer or HAL and use them for Zwave or switching to a panel like the Elk that has Zwave support (if the Omni doesn't).