Goto /etc/sysconfig/network-scripts. In there there are files like ifcfg-eth0 and for madwifi Atheros cards it should be ifcfg-ath0. Open that file in an editor as root and change a line like ONBOOT = NO to ONBOOT = YES. Then if you have eth0 or others edit them and change yes to no for the onboot line.
Example of mine.
# NAME='Linksys WPC55AG'
# KEY=xxxxxxxxxx # 64bit wep
KEY=xxxx-xxxx-xxxx-xxxx-xxxx-xxxx-xx #128bit wep
# IWPRIV="authmode 1"