I'm not sure what you mean by "accessible". You should to make that script "executable".
Show us the output of the following command:
ls -lahs /etc/rc.d/rc.networkmanager
The output should look like this:
4.0K -rwxr-xr-x 1 root root 1.7K Aug 14 2012 /etc/rc.d/rc.networkmanager*
If you don't have the "x" in "-rwxr-xr-x", run this:
chmod +x /etc/rc.d/rc.networkmanager
...and you'll be good to go.
Otherwise, I recommend making your own thread...this one is marked as [SOLVED] ;-)