I totally disagree with the comments above. i think it is next to impossible to press the bearings in perfectly square. My theory is... When you tighten the crank, the bearings will get re-aligned into the correct position they are meant to be in up flat against the circlips. My other theory is the bb shell will ovalise over time anyway because of the forces being exerted on it.

When i was rushed one time i pressed my bb30 bearings in by hand. It hasnt caused me any problems as yet (touch wood)