GSX doesn't add a custom event id to be called. You could use this method:
- Assign something ( like a joystick button, or a VR controller button ) to send the same key combination used by GSX, for example CTRL+Shift+F12
- Once the GSX menu is open, you can use these Events KEY_SIMCONNECT_MENU_1 to KEY_SIMCONNECT_MENU_9, and assign them to the "One", "Two", "Three", etc. up to "Nine" voice commands, which will select the relevant option in GSX.
The nice thing about this is that, once you configured the 9 voice commands to send the standard Simconnect menu events from 1 to 9, they will work with every application that has a menu, not just GSX, but also SODE, FS Passengers, etc. . The only thing different would be the command to start the different menus.