I hope this will make it somewhat more straight forward for you.
You will need three files that are on your distribution disk.
Untar these three .tgz files in a directory where you can play with them.
In the directory created when you un-tared the microcode tarball, copy the file named ipw3945.ucode to /lib/firmware.
In the directory created when you un-tared the regulatory-daemon, copy the ipw3945d to /sbin
in the directory created when you un-tared the kernel-modules, run the following. make, make install, depmod
Now, as root enter: modprobe ieee80211
Then enter: modprobe ipw3945
Then enter: /sbin/ipw3945d &
Then enter: dhcpcd eth1
You should now be connected to your neighbors WiFi