The part in bold are the supported features try:
Number GuestfanLincFan “Guest fanlinc fan” {insteonplm=“XX.XX.XX:F00.00.1C#dimmer”}
BTW, I’m in the process of porting the insteonplm binding to OH 2.5. I’m looking for volunteers to help test. Check out New Insteon 2.5+ binding if you are interested.