Change VPN Shared Secret through CLI

We have changed the VPN Shared Secret on the server. We have about 50 VPN users who are currently in the office, but will be using the VPN tonight when going home.

Is there a command-line / AppleScript way to update this shared secret in bulk across all computers?

I have come across the security command which allows you to modify passwords in the keychain, but I can't figure out the exact syntax to update the VPN shared secret.

I also looked at the AppleScript dictionaries for System Preferences and Keychain Access.

System Preferences has extensive AppleScript commands for altering network settings, but I haven't been able to find the right setting the change the VPN shared secret.

Keychain Access doesn't seem to have any AppleScript dictionary at all.

Can anyone offer some advice as to how I might be able to update 50 users' VPN Shared Secrets efficiently?