Setting Object Anchor

Hi everybody!

I'm trying to access this little ui-element one here via shortcut.

Unfortunately it can't be set in keyboard-shortcut preferences.

I use it quite often, and it is a pain to hit one of these 5x5 pixel-sized squares with the mouse.

This property can be used with e.g. "rotate myRectangle angle 45 about center" via applescript,
but can it also be set like if pressed by a human in the user-interface with or without an active selection?

In the image you can see the result after pressing ctrl+7 (top left) for example.

bottom-right would be ctrl+3 and so on...

ctrl+7   ctrl+8   ctrl+9

ctrl+4   ctrl+5   ctrl+6

ctrl+1   ctrl+2   ctrl+3

If, at all, how can this be done? Thanks in advance.

Kai