A walkthrough at last.

[Liz Shaw]

Originally Posted by forlik

You can stun this guard also. You will get 1 stunned instead of 1 killed.

You can also throw a fragile object (eg. glasses and cups) at the guard if you aim for his head. But don't try it in MoTMod, for some reason the guards in the other room will investigate the noise...

Also, the waiter's suit CAN be used. Maybe you're referring to the manager's suit...

hb2, security guards, cooks and waiters are all of the type "Soldier", meaning you can use one of these disguises to get into the diplomat's room easily.