You don't really need to shift your butt all the time. I just try to stand or raise my butt with my outside leg. After a while it becomes a habit and smooth.
that phrase "weight the outside peg" ANd it is true, but don't take it Exactly literal!
Putting pressure on that peg is the result of putting down pressure on that whole leg in a corner as you press down on the bike completely. this would of course be on the "high side " of the turn. shifting you rear on the seat helps apply that downward force, it in turn allows a rider to PRESS harder on that particular peg.
you should just use your body wieght and shift it to that side of the bike. Pressing down on that side you want to "wieght" helps you "push" more with your knee and side of your leg. Do not take this to the absolute literal point and lift your butt off the seat, then all your asking for is a funny looking corner crash!