IIUC this feature scales&translates the document so as to minimize the margin (and hence maximize the size of the printed text, without cropping).
Yes, that's it.
If that's the case, no I sadly don't know of a Free Software tool that does that for you.
Sad news.
I would love to see a tool that does this automatically for me (especially if it can do it for 2-up as well).
Me too :-)
Fundamentally, it shouldn't be that hard. IIUC running the PS (or PDF) file through "gs -dSAFER -dNOPAUSE -dBATCH -sDEVICE=bbox" should return the needed info about area actual used by the document, after which it should be easy to scale/translate/rotate to make it fit on a page of any given size. But I never got around to trying it out.
Would be nice, if somebody could take this up ... Andreas Gösele