run mcintosh mc 30 with two speaker systems?

i'm up to get a pair of mc 30 that I want to run with two loudsspeaker systems (2x8ohm plus 2x4ohm). in the users manual there is a hint for connecting multiple speakers, but i don't get the clou how to do so in practise. does anybody have the know-how in here?
I would advise against running speakers with different impedances simultaneously from the same amp.