easiest would be to setup the SD card on a B/B+, and then move the card and wifi stick over to the A or zero.
The dependencies are listed in a separate file. So for wifi.tcz, the dependencies are in wifi.tcz.dep Dependencies are cascaded..... which is why I suggested the above.
tce-load -i extension.tcz loads from local. But in your case, you would just download all of the required extensions manually, then place wifi.tcz in the onboot.lst