1. the ipkg feeds should have all the kernel modules already
2. install a kernel module with this command: ipkg install 'name-of-kernel-module'

If the kernel module you want to install is available for Unslung, but not on the ipkg feeds, they can be browsed here: http://ipkg.nslu2-linux.org/feeds/unslung/modules/cross/stable/

1. manually download the package with this command: wget http://ipkg.nslu2-linux.org/feeds/unslung/modules/cross/stable/'name-of-package'
2. change to the directory where you manually download the package
3. manually install the package with this command: ipkg install 'name-of-package'

NOTES

1. you many need to use: 'ipkg --force-depends install' instead of 'ipkg install' because there is a broken dependency on the kernel image.
2. the ipkg conf file that contains the location of the kernel module ipkg feed is: /etc/ipkg/oe-feed.conf