Cross copying drivers from different releases?

Hi, I have a laptop with the Intel 4965 wireless chipset.
I have an old revision of the driver for 7.0. But apparently several improvements have been made and comitted to HEAD aka 8.0.

Would it be possible to just cross copy the /iwn modules directory from 8.0 into 7.1 and build?

No. You'd need dev/ too, but too many changes in 8.x kernel have been made, that I'm 99.9% sure it won't compile.
You will have to wait for an MFC of the changes, ask for backported patches or do it yourself(tm).