You have a bit of a catch 22 situation because to resolve your problem you need access to the web.
If you can't do it find a friend who can access http://www.madwifi.org
and download the following file madwifi-hal-0.10.5.6-current.tar.gz.
They could email it to you. Put it in your Home directory and then do the following in a terminal.
tar zxvf madwifi-hal-0.10-5.6-current.tar.gz
This will open the archive in a new directory madwifi-hal-0.10.5.6-r3861-20080903; go into this directory e.g
and type the following.
(for the next bit you have to be root) so
You must have the headers for your kernel installed for this to compile.
Hope you are successful