[OS X TeX] 2in1 package for lettersize?

[Christopher Menzel]

There's a nice little package called 2in1 that renders two pages on a  
single sheet in landscape orientation.  However, the package only  
works properly for A4 paper.  I tried hacking the code with some  
success, but I am unable to get the page number for each rendered page  
properly centered beneath it, and my elementary TeX skillz are not up  
to the challenge. Does anyone know of a comparable package that works  
with lettersize?  Nothing I've found seems to do what I'm looking for.

Thanks.

Chris Menzel