Third-Party Seatbelts | JG Scripts Docs

The seatbelt key bind, button in the F6 vehicle control menu, sound effects, and indicator light within JG HUD will still work when using a third-party seatbelt integration!

Within config.lua, set Config.UseCustomSeatbeltIntegration = true. Ensure that Config.EnableSeatbelt = true, or it won't work.
Head to framework/cl-functions.lua and find Framework.Client.ToggleSeatbelt. There are two parameters, vehicle & seatbeltOn. seatbeltOn will be true if the seatbelt has been enabled, otherwise false. If you have multiple exports, one for enabling the seatbelt and one for disabling, you'll need to use seatbeltOn in an if statement; for example:

if seatbeltOn then
  exports["my_seatbelt_script"]:enableSeatbelt()
else
  exports["my_seatbelt_script"]:disableSeatbelt()
end