Excel 2002

I need to return in column Z the last non-blank value in
columns D, F, H, J, L, N, P, R, T, V, X (every other
column starting with D) [or conversely, the first non-
blank working backward from column z and hitting every
other column].

I can use nested IF statements using ISBLANK(X3), but only
up to 7 and I need 11.

What formula (or VBA if a formula isn't possible) could I
use to accomplish this?

Thanks for any help!