Don't use rpgserv... It sucks ass and crashes servers..
If you want to host a non-dedicated server, open up your autoexec.cs
insert this line
$AdminPassword[5] = "changeme";
Save it and close..
Click start run.. yourtribesdir/Tribes.exe -mod rpg
You should know what to do from there.. #admin changeme would give you admin 5
For a dedicated server..
There are many different ways to run a dedicated server.. The best way I have seen is running through infinity spawn.
If you would like to run a dedicated server, I can make a .bat for you and give you some scripts that will make things a tad easier on you...
But I won't do this unless you are going ot make a perm dedicated server.