MacConkeys instead of Xgal/IPTG selection?

[Robert Rumpf]

I've heard that the alpha-complementation-based color selection using 
lacZ-phagemids, lacZ deletion host cells, and Xgal/IPTG plates can also be done
using the same phagemids/host cells but plated onto MacConkey's agar.  Is this 
true, how is it done, and what's the mechanism for color selection?  I 
appreciate any help you can give...