lattice: adding text between grouped panels?

How one can add a text (e.g. the labels of an axis)
in a space between grouped panels which was created
by using the argument ``between''?

Example:
	data(barley)
	dotplot(variety ~ yield | site * year, data=barley,
		between=list(x=c( 0, 0, 6 ))
How to add labels for the y axis in the space in the middle?


Thanks

Wolfram