par(mfcol=2, mfrow=3) equivalent for trellis

Dear friends of lattice,

I know how to position trellis plots with print(...,split,more=T) or
(...position).

Sometimes I wish I had something like the old "par(mfcol=2, mfrow=3)"
mechanism, where the next free viewport is automatically chosen. I
tried fiddling with grid-viewports, but could not find an easy
solution.

Did I miss something?

This is definitely not doable right now (since print.trellis by default 
plots on a new page), but it can be implemented if there's interest. 
The easiest solution would involve changing print.trellis to get the 
default 'split' from some sort of user defined setting. Most of the 
mechanism required for this is already in place. 

A grid level implementation of par(mfrow) may help, but I don't think 
that's in keeping with grid's design goals.

Deepayan