Cell Renderer in a datagrid component

Hi,
I’ve created a custom datagrid column which contains buttons according to the content of the row.

In each row I have a movieclip which has 3 frames (for 3 possible actions - play / pause / stop), problem is I don’t know how to access the cell renderer for each individual row,
in order to change it according to its contents.

How can I do this?

Thanks.