Use psnup or pstext or enscript.
These programs redefine the PostScript ``showpage'' command to do multiple PostScript pages per physical page. If one program doesn't work with a complex document, try out other ones.
Some PostScript programs can't work with these programs because they break the EPS conventions (See Section 9, ``Encapsulated PostScript''.). The reason is that some Postscript operators (such as initgraphics, the list is in the Red book) change the printer state so "violently", that software trying to do things like n-up will get confused. Theoretically, an EPS shouldn't have any of these operators, but it may not really be an EPS, or there may be a weird interaction between TeX, the EPS and the inclusion mechanism that breaks psnup.