To try out the API, there is a simple command-line tool included here, called example.py. To use it, provide it with a country and language code via the -c and -l flags, respectively:

$ python3 example.py -c US -l en-US

LG accounts seem to be associated with specific countries, so be sure to use the one with which you originally created your account. For Korean, for example, you'd use -c KR -l ko-KR.

On first run, the script will ask you to log in with your LG account. Logging in with Google does not seem to work, but other methods (plain email & password, Facebook, and Amazon) do.

By default, the example just lists the devices associated with your account. You can also specify one of several other commands:

ls: List devices (the default).
mon <ID>: Monitor a device continuously, printing out status information until you type control-C. Provide a device ID obtained from listing your devices.
ac-mon <ID>: Like mon, but only for AC devices---prints out specific climate-related information in a more readable form.
set-temp <ID> <TEMP>: Set the target temperature for an AC device.
turn <ID> <ONOFF>: Turn an AC device on or off. Use "on" or "off" as the second argument.
ac-config <ID>: Print out some configuration information about an AC device.

Credits

This is by Adrian Sampson. The license is MIT. I also made a Home Assistant component that uses wideq.