Mavic method or as Barnetts in Chapter 17 calls it stabilizing the true.
It is a slightly risky method because if you overshoot you can plastically deform the rim. This is especially the case with rear wheels when the cassette side is up.
Place a block of wood on the floor and place the wheel on it such that the hub axle (QR skewer removed) rests firmly and squarely on the block. Place your hands at 180 degrees to each other on the rim and at the positions of spokes coming from the nearer side of the hub. Push down with sufficient force to make the spokes coming from the bottom side of the hub nearest your hands to just go to zero tension (this is where the risk comes in - DO NOT START BY PUSHING TOO HARD >>> with all your weight and elbows locked). Once you get a feel for sufficient force apply it again and again rotating the next pair of upward facing spokes (8 pushes per side with 32 spoke wheel). Flip the wheel over and do the same all over again.
You can get more details from Barnetts Manual Chapter 17 or by visiting Mavic's Technical site. I prefer the description from Barnetts.