Thanks' for the suggestions. But maybe there is such a thing as a 4-way "Super" or "Mega" switch on the market that is not as limited as the traditional 2-pole 4-way switch that you mention?

Well anyway, I do realize that it is a bit much to ask you to do a diagram but would it be possible for you to at least give me a hint on how to do the push pull wiring as in your first suggestion?