I assume you already have insteon terminal set up, but here are a couple of lines from init.py to define devices so I have shortcuts for programming:
# device definitions
modem = Modem2413U("test_modem", "44.85.d6")
# dimmers
Office = Dimmer2477D("Office", "45.a9.ae")
bedCeiling = Dimmer2477D("bedCeiling","46.a2.4f")
# micro dimmers
stairs = Dimmer("stairs","2b.3b.de")
# switches
backPorch = Switch2477S("backPorch","34.0A.EC")
And an example of adding two items to scene 12:
Office.addResponder("44.85.d6",12, [0, 28, 1])
bedCeiling.addResponder("44.85.d6",12, [35, 28, 1])
modem.addController("45.a9.ae",12)
modem.addController("46.a2.4f",12)
So in this example, the scene sets Office to 0 brightness, ramp rate 28, button 1 (everything but keypadlinc is button 1 I believe). It sets bedCeiling to 35 brightness, 28 ramp rate, button 1. Then you have to tell the modem that those two devices are in the group - which is the 2 lines for adding to the modem. Brightness and ramp rate are on a scale from 0-255.
One final note is if you make a mistake you’ll have to remove the devices individually from the scene then add them back in. Like this:
bedCeiling.removeResponder("44.85.d6",11, [255, 28, 1])
modem.removeResponderOrController("46.a2.4f",11)
From what I read it’s recommended to start at group 11 because 1-10 are used for other things in the insteon system. You can use up to group 255 - which would be impressive. I’m at like 40 dimmers/switches in my house and have only used through group 32 I think. Good luck!