If you can't find a module package for your kernel you will have to compile the modules from source. You can get it with
wget
http://snapshots.madwifi.org/madwifi-ng-current.tar.gz
Then issue a
tar -zxf madwifi-ng-current.tar.gz
Then go to the created dir (mine was as follows, your may differ)
cd madwifi-ng-r1531-20060427/
Do a "ls" to see what you can find:
ath contrib include Makefile.inc regression THANKS
ath_hal COPYRIGHT INSTALL net80211 release.h tools
ath_rate docs kernelversion.c patches scripts
BuildCaps.inc hal Makefile README SNAPSHOT
Then read the INSTALL file, for example with "less":
less INSTALL
You can leave "less" by pressing "q".
Just follow the instructions... you can probably install all the dependencies with "yum".