Narrower zones in Omega
You cannot do this with Omega as its not part of the structure of the 960 grid system. Your best bet is to do it via CSS. 

First you you would take the largest section, which would be the middle one. Say its 1000px, now the header and footer would also be 1000px. You would then modify the inner div in those regions to be 980px (10px on each side) to get the effect your looking for.