[MP2]

All that is necessary is this:

pawn Код:

#define ClearChat(%0) for(new i=0; i<20; i++) SendClientMessage(%0, -1, " ")

public OnPlayerRequestClass(playerid, classid)
{
    SetSpawnInfo(playerid, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0); // Without this you'll be kicked when you spawn. Set it to wherever you want.
    TogglePlayerSpectating(playerid, true);
    SetTimerEx("login_dialog", 100, 0, "i", playerid);
    return 1;
}

forward login_dialog(playerid);
public login_dialog(playerid)
{
    SetPlayerCameraPos(playerid, x, y, z);
    SetPlayerCameraLookAt(playerid, x, y, z);
    
    // Show dialogs etc. here
    
    ClearChat(playerid); // Custom macro to send some empty clientmessages
    return 1;
}

Result:

http://www.movieserv.net/files/login_dialog.png

If you need messages in chat, remove the ClearChat() line, but I'd recommend keeping it clear as on low resolutions the chat ends up over the dialog.

To spawn players after that, it's extremely simple:

pawn Код:

TogglePlayerSpectating(playerid, false);