Although mouse click events are not the easiest way to interact with TurboHUD (because the Diablo 3 client also processes all the clicks), it's the most intuitive. When Dys told me how to check mouse button state in TH, I ran with it and have been spinning out plugins with click event functionality ever since.
This plugin polls mouse state and generates left and right mouse click events (frequency capped by TH's refresh rate, which maxes out at 60 FPS). It's a bit primitive, but works within the boundaries of the original TurboHUD v9.0 restrictions. Plugins that want to be notified of these events can simply implement the ILeftClickHandler and/or IRightClickHandler interfaces.
Most recently, I added the ability to substitute a keyboard press for a mouse click with IKeyEvent ClickEventHandler.SimulateLeftMouseClick and ClickEventHandler.SimulateRightMouseClick. Using my new Hotkey library, it treats the E key as the left mouse bottom and the R key as the right mouse button. You can specify your own keys for that, or set the aforementioned properties to null in a Customize function/configuration file (or comment out the key definitions in the Load function) to not simulate presses with any keys.
LibClick (Last Updated April 20, 2021)