Illustrator users? Registration Point

Hi all.

I am working with an artist at the moment for some flash stuff but he is away for a week.

I was wondering if someone can assist me with this:

Say in Illustrator, you draw a circle and group it.

If you check out the Info pane, it will assume that the registration point of that group is the top left. However, how can i centre the registration point.

In other words, when i place the group at 0, 0, id like to only be able to see a quarter of the circle as opposed to all of it.

Does that make sense?