Knoppix 5.3.1 and kde 4.0

Hi,
Wonderful and fast as a light...with my AMD 1000, 1GB ram and ATI-Radeon 9550 PCI
How can I boot in live-mode with kde 4.0 as experimental option?
I can find't it in cheatcodes
Thanks
Jose :roll:

Code:

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desktop=kde4

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does not appear in the F3 help screen, but is working fine ;-)