[roundout]

theoretically, you shouldn't have to adjust the power at all. if you fly the maneuver correctly from start to finish, you should end up at the same airspeed and altitude you began at. how likely is it that you will fly perfectly or won't get bumped around by summer thermals? doubtful at best, but i advocate correcting errors with the yoke and rudder first. the power is the last thing i change in trying to make a lazy-eight acceptable. i know quite a few people who fly lazy eights with one hand on the trim wheel and only rudder input to steer the plane. there's nothign that says you can't. i've even been known to try this to really emphasize the intended laziness of the maneuver.