I will not go into why you wanna do this,but if you don't know ssh is more secure as repo
said and you should use it,but if you must do it,edit
In this file, find the line for disable
and change it from the value "yes" to "no".
After changing the above value,as root,type the following command:
Telnet is usually started with
chkconfig telnet on
To enable root login edit the file /etc/securetty
and add the following to the end of the file:
Now you can have 5 sessions as root to the server.