[ubuntu] Workaround for failing multitouch: holding a key to scroll?

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http://ubuntuforums.org – I'm running Ubuntu 11.10 on a laptop that it apparently doesn't support multitouch on. Thus all my touchpad can do is move the mouse pointer, it can't scroll. But would it be possible to work around this by making it so whenever I hold the, for example, AltGr key and touch the trackpad, it will scroll instead of moving the pointer? How would I do this? (Hardware)