The trick is positionate on the rotation axis of the asteroid, and use Q or E to rotate at it's speed. You need a good reaction wheel for that. If you want even a bigger challenge, use one of the mods that nerf the reaction wheel...
Is there any way to use the stock icons for symmetry? I rather prefer the stock icons, than the nR, M and MM (even if I loose some extra nR symmetry added by the mod).