Originally Posted by Pleiades

Cable tie the sprocket/carrier to the spokes to hold that in place.

Extra generous blobs of grease on the spacers tend to keep them in check.

Lever the pads back into the pistons (keeping an eye on the fluid level in the master cylinder) gives extra play needed.

I also use a piece of wood resting under the wheel to act as a lever/chock to lift the wheel, so I can concentrate on getting everything aligned without having to worry about supporting any weight at the same time.

There are other ways, probably better ways, but this is what seems to work for me.