more sessions within kdm session

[Pol]

I would like a local user to start its own session, through ssh, within the 
kdm running session of another user. Both users are local.
How should i start that script? Should i launch kdeinit, before the users
applications?
How to restore that user's session? how to save on exit?

There will be differences in procedure between my current kde 3.5.8 and kde
4?

Thank you for your help

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Pol