[Divergent]

enum playerdata
{
pRegistered,
pPos[3]
}

OnPlayerSpawn(playerid)
{
if(PlayerData[playerid][pRegistered] = 0)
{
SetPlayerPos(playerid, x, y, z); // pick these
}
if(PlayerData[playerid][pRegistered] = 1)
{
SetPlayerPos(playerid, PlayerData[playerid][pPos][0], PlayerData[playerid][pPos][1], PlayerData[playerid][pPos][2]);
}
return 1;
}

Under OnPlayerDisconnect add
GetPlayerPos(playerid, PlayerData[playerid][pPos][0], PlayerData[playerid][pPos][1], PlayerData[playerid][pPos][2]);