From what little knowledge of mapping and server setup I know, you will need 2 things. You will need:
A. A script for the server that removes all weapons from the players except for the ones chosen.
B. You need to leave out buy zones in the spawn areas for the map.
When it comes to the script for the server, I'm sure most people will have that taken care of. As for the map, you just need to leave out the buy zones. I'll warn you now though, my info is limited when it comes to mapping so I would wait for someone else to say something in case I am wrong.