dvips and landscape

[Raphael Clifford]

I am producing a landscape document using prosper and lyx 1.3.2.  When I 
view->postscript and then choose landscape in gv the page is cropped 
about 2 thirds of the way to the right (presumably it is actually 
1/sqrt(2) of the way across). This is because it is rendering the page 
as a4 portrait even in landscape mode.

This happens because lyx calls dvips with -t a4, as far as I can tell. 
There seems to be no need for this and it doesn't work.  How do I turn 
this off (export->latex and then dvips without the -t a4 option works fine)?

Cheers,
Raphael
P.S. I am running redhat 7.3 and I have set the default paper size to A4 
in lyx and dvips.