^^that was a general reason...
you are right the cam dictates it on out engine and in sohc in general but on our engine the adjustment (advancement) will allow you to move the power curve to a specific area in the rpm this is ideal for drag racers who need all the power at the top end Retarding will do the opposite....
your right ovelap is for dohc i feel stabed and moronic yes.... sorry for that...

 

so, lets say I want to put all the power of MIVEC @ 5k rpms... how do I go about that?

 

do it on a dyno.....
remember that mivec is not a 'power adder'perse just the valves opening a bit more...
so if you want to have it like that (at 5k) i invite you to do the procedure on a dyno to be sure what you are doing.... anyway the cam still 'produces' til 6300 or more i guess...