And if your are using password for x11vnc

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#!/bin/bash
dbus-send --print-reply --system --dest=com.nokia.mce /com/nokia/mce/request com.nokia.mce.request.req_tklock_mode_change string:unlocked

x11vnc -usepw -timeout 20 -bg -grabkbd -cursor X
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Setting a password for x11vnc

Open X Terminal (or SSH into the N900 and login as user) and type x11vnc -storepasswd

Enter password when prompted

Gain root

As root user, edit /usr/share/applications/hildon/x11vnc.desktop

Replace the line that says "Exec=/usr/bin/x11vnc" with "Exec=/usr/bin/x11vnc -usepw"