I'm sure that FC6 has a 2.6 kernel. From my /etc/modprobe.conf file:
# /etc/modprobe.conf (old location for Linux 2.6+ config)
# The use of this config file is deprecated.
# Instead, create files in the /etc/modprobe.d/ directory
# containing modprobe options.
# For more information, see "man modprobe.conf".
Try that route, post what you did if it doesn't work; which means the
contents of the file you edited and your error message.