All Garry's Mod donation systems should provide a way for the server to run a console command when a donation occurs.
Billy's Whitelist provides the gas_jobwhitelist console command which allows automated whitelist management.
Type gas_jobwhitelist in your server's console for instructions.
Your donation system should be able to automatically insert a player's SteamID into the command. Please refer to your donation system's instructions to learn how to do this, or contact their support.
