Is your computer connected to the Internet? If you can, do it the way Sashank999 tells you.
if not, do it the following way.Download the following extension manually.And download the corresponding *.tcz.md5.txt and *.tcz.dep(which may not exist) for each extension.
firmware-iwlwifi.tcz,wifi.tcz,
wpa_supplicant-dbus.tcz,libnl.tcz,
dbus.tcz,expat2.tcz,acl.tcz,attr.tcz,libcap.tcz,
openssl.tcz,readline.tcz,wireless_tools.tcz,
wireless-4.2.7-tinycore.tcz,libiw.tcz
Then...
tce -i firmware-iwlwifi.tcz
tce -i wifi.tcz
sudo wifi.sh