Update: I compiled now a MeeGo Tablet version and created a *.rpm package for the Sender Application: TcpIpKeyboardSender-0.0.3-3.i586.rpm

So, if anyone has a MeeGo Tablet like the ExoPC or a Lenovo IdeaPad - you are now able to send keystrokes to your N900.
At the ExoPC you have to connect a USB Keyboard to use my application. The Lenovo IdeaPad has the integrated keyboard as advantage.

If the virtual Keyboard doesn't disappear after you have changed the settings, simply close the application and reopen it afterwards. The new settings are applied now and you can start typing.