tankut is right, you will have to re-think your approach... one method that you may find useful is to use "poly bevel".
if you extrude your faces (as you have done, faces kept apart) by a specific amount (e.g. 0.8), but DON'T scale them, then immediately do a poly bevel using the SAME size (0.8) (you may have to change a few polyBevel settings, to merge verts and so on..), it should produce the effect you want albeit with slightly vertically-thinner faces, but it's simple to y-scale the faces after the bevel
the only problem with this is polyBevel destroys your UVs (not a problem if you don't have any! 
)...
:nathaN
here is an example script to demonstrate, you can run it a line at a time if you want to see the result at each step.. (make sure you run it on a NEW scene)
polyCube -w 4 -h 1 -d .25 -sx 5 -sy 5 -sz 1 -ax 0 1 0 -tx 1 -ch 0;
scale -r 0.5 1 1 pCube1.vtx[1:2] pCube1.vtx[7:8] pCube1.vtx[13:14] pCube1.vtx[19:20] pCube1.vtx[25:26] pCube1.vtx[31:32] pCube1.vtx[37:38] pCube1.vtx[43:44] pCube1.vtx[49:50] pCube1.vtx[55:56] pCube1.vtx[61:62] pCube1.vtx[67:68];
polyExtrudeFacet -localTranslateZ 0.08 -kft 0 -d 1 -ws 0 pCube1.f[10:14];
polyBevel -offset 0.08 -sg 1 -ws 1 -fn 1 -mv 1 -mvt 0.001 -sa 0 pCube1.f[10:14];
scale -r 1 3 1 pCube1.f[65:69];