You can subscribe to specific data change Events, on specific Devices, using the [tt]luup.variable_watch[/tt]. This is not a blanket subscription to all events produced in the system as that would be a LOT of events.
Are you trying to watch a dimmer or an on/off switch? The variable associated with SwitchPower1 is “Status” instead of “LoadLevelStatus.” The …SwitchPower1 urn can be used with dimmers or switches to determine if the device is on or off. To watch for a change in brightness watch the …Dimming1 urn and the variable “LoadLevelStatus.”