Well, you can start a non-dedicated server in-game by going to the create server option instead of play game. If you've loaded RPG mod, just select RPGmap5 and you're good to go. Also, if you want admin passes, stick this into your autoexec.cs in your Tribes\Config folder, changing accordingly:
$AdminPassword[1] = "1";
$AdminPassword[2] = "2";
$AdminPassword[3] = "3";
$AdminPassword[4] = "4";
$AdminPassword[5] = "5";