1. Download Return to Blockland in that link.
2. Put it in your add-ons folder.
3. Start Blockland.
4. Goto Options->Controls, scroll down.
5. Once you find RTB in the list set the keys.
6. Start a server.
7. Press the Server Control Manager key thing.
8. Change options.
9. Press the send button, and you're done.
Most likely some names and stuff are wrong.