Pair 2GIG-CO8-345 with GC3

I am struggling trying to program/pair the 2GIG-CO8-345 CO detector on my GC3 panel… I may have got lucky discovering the serial number but the CO8 is not listed as a device. Please provide step by step instructions on how to get this device set up.
Thank you,

The CO8 uses the same steps as the CO3, found here: