How do I set the state of a three-state checkbox?

I am using AutoIt to automate a Windows application for testing. I would like to be able to set the state of a three state checkbox that is by default indeterminate.

I have tried using ControlCommand(.., .., .., "Uncheck", ..) to set the "unchecked" state but it remains at indeterminate.

When I use "Check" in ControlCommand it moves the CheckBox from Indeterminate to False because that is the order of clicks:

1. Indeterminate
2. Unchecked
3. Checked

Is there a way to set the state programatically using AutoIt, without assuming the default state and counting the number of clicks myself?