without reading that howstuf works page...

cam has 2 sets of lobes (so say 8 valves, you have 16 lobes) in normnal running half of them are in contact with the valves, and have "normal" profiles... all's happy

when you start caning the shit out of the c the cam physically moves across a bit (so moves sideways) which will mean the normal profile lobes are no longer in contact with the valves, and the new more meaty lobes are touching the valves...

feck knows how it moves, or even if im talkin about the right type of thing (iirc vtec and vvti are actually different, not just different names for same thing )

but thats how i understand it