'Set the coordinates of the label.  By default, the x
coordinate of the y label is determined by the tick label
bounding boxes, but this can lead to poor alignment of
multiple ylabels if there are multiple axes.  Ditto for the y
coodinate of the x label.
You can also specify the coordinate system of the label with
the transform.  If None, the default coordinate system will be
the axes coordinate system (0,0) is (left,bottom), (0.5, 0.5)
is middle, etc'

def set_label_coords(self, x, y, transform=None):

    self._autolabelpos = False
    if (transform is None):
        transform = self.axes.transAxes
    self.label.set_transform(transform)
    self.label.set_position((x, y))
    self.stale = True
