Unfortunately, the 2010 FIFA World Cup video game for Xbox 360 does not have a dedicated "rainbow flick" mechanic. This technique, which involves a specific ball control and a flick of the wrist, is a more modern feature that was introduced in later FIFA games.
However, there are some similar moves you can perform in FIFA 2010:
While these moves might not be as flashy as a "rainbow flick," they can still help you control the ball effectively and score some impressive goals.
Remember, mastering ball control and timing is crucial in any FIFA game. Keep practicing and you'll discover your own techniques to outwit your opponents.