This is to document a work around for loading the ipw3945 driver on Gentoo based systems (tested on 2.6.19-gentoo-r5 + udev.) There is an issue with IEEE 802.11 dependencies even though it is using the in-kernel version.

Compile native IEEE 802.11 support into the kernel as of version 2.6.19. Then install the ipw3945 driver, ipw3945d daemon and ipw3945-firmware.

Go to your modules directory and open the modules.dep file. On Gentoo, go to /lib/modules/2.6.19-gentoo-r5/modules.dep file and then go to the ipw3945 line in the file. On Gentoo, it will should read... /lib/modules/2.6.19-gentoo-r5/net/wireless/ipw3945.ko: /lib/modules/2.6.19-gentoo-r5/kernel/drivers/base/firmware_class.ko
... with all the ieee80211 file references removed.

Then make sure /etc/udev/rules.d/70-persistent-net.rules doesn't have duplicate NAME="eth0" entries. This will ensure udev properly loads the wireless to eth0/eth1 and the wired to eth0/eth1 instead of the wired card overwriting the wireless card ifconfig entry. In this situation, the wireless card will "mysteriously" not load correctly in ifconfig. ipw3945 should be loaded at runlevel time and the card should start working after boot without problems.

Please reply if you guys have any problems.
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