Well, from this link...http://wiki.linuxmce.org/index.php/Running_the_Insteon_PLM_Driver_for_the_First_Time
we find the following...
Running for the first time
Initially, the driver needs at least ONE active lighting device. To add a device to the Insteon PLM, you will need to hold down the set button on the Insteon PLM for 10 seconds. Then go to a light and hold down the on button on a light until the light flashes. The driver will download this device's database and attempt to extract other Insteon ID's from it. Then it goes out and PINGS those devices in turn, to find out what kind of device they are. Once that is finished, it attempts to download each device's database, in turn, looking for more Insteon devices. This procedure, nicknamed 'Spidering', continues until all devices and device links are recognized. Once this 'Spider' is complete, the driver reports all detected devices, to LinuxMCE.
I find this ambiguous. The work "initially" could mean before wizarding the device, or it could mean after the wizard but before using it. I called tech support at Smarthome today. He said the PLM had minimal documentation because everything depends upon the software. He said my light switch and PLM have never been linked, based upon my description of the behavior. The PLM set button only needs 3 seconds to enter link mode, not 10. The light switch should beep twice and the LED will not remain blinking after link is established. That has never happened. Interference could be an issue - I might try turning off all circuit breaker in the house except the ones for the computer, PLM and light circuit. The lights are on an AFCI breaker but this is not an issue. He said that the link is usually accomplished by the software instead of manually, but he was not familiar with LinuxMCE. He recommended that I consider purchasing a lamp module and performing my initial tests with that device plugged in to the PLM's receptacle.