This will not be easy. i see two possible solutions.
You could use a custom itemRenderer. This will require that
you find some way to identify the dataProvider collection index
from within the renderer, and set the renderer to editable when
that index is 0.
Or you could create a composite component using two
dataGrids, one with a single row for the editable columns. There
are examples available on combining two DGs this way.
Again, this will be difficult, so be sure that it is
absolutely required and consider some other UI approach if posible.