Hi @vikingsteve,
Glad to here you like slash commands!
Unfortunately we don't have any way to distinguish between users logged in and sending requests from within a certain network or from outside it. You might be able to set up a load balancer to block certain API calls from any external IP address but I can't guarantee that will work.
If you think this is something that would be useful in the product could I have your help creating a feature request?
Cheers