different vertical margins for odd and even pages?

[Robert Neumann]

hello, 
is there a way to define different vertical margins for odd and even pages? 
(I'm designing Vocabulary-Cards with lyx and on the odd side I need a header 
and a footer, but on the even side I need neither one - but space to write the 
anwer...) 
One of my Ideas was, to have small margins and then a negative headsep and 
footsep. this works for the header fine but not for the footer, the minus is 
ignored in the footsep 
 
thanks 
Robert