"How did I do it? That was quite an easy trick.", said Greg and started to tell his story.
Back in the Earth Temple when he was 'ordered' by Carter to obtain the cube, Greg noticed that the statue was quite old. Even though the place looked extremely detailed and nonintact, the statue had several cracks around its surface. Especially at the arm part which held the cube up into the air.
When Greg noticed this fault of the statue, he instantly thought of a great plan.
First, he made sure to jump onto the statue's palm with a strength that was not too obvious but would help him break the arm off, helping him to continue with his goal.
In the beginning, he wasn't quite sure if he could pull it off, but to his surprise, only a small touch was needed to make the stone statue to collapse, which was surprisingly great.