[flexcoders] Datagrid non-editable but want to tab between columns

[flexcoder2008]

I have a datagrid that has some columns formatted using item renderers.  I want 
to enable keyboard navigation so the user can tab across the columns.  I know 
that this behaviour is built in to the datagrid if the editable property is set 
to true, but how do I accomplish this if I want the grid to be read only? I 
just want to be able to tab to a particular column and capture keyboard events 
from there.