GRANT ALL ON eqemu.* TO 'gmaccount'@'%' IDENTIFIED BY 'gmpassword'; is the sql to create an account named "gmaccount" with the password "gmpassword" that can access the database named "eqemu" from any ip address (the % is a wildcard). As Trevius said, if you know the gm has a static ip or always connects from a specific hostname, you can change the ip to be like '173.22.166.22' or '192.168.1.%' (for any ip on the lan), or even '%.example.com'.
You should look at
http://dev.mysql.com/doc/refman/5.1/en/grant.html to see the syntax for grant as you probably don't need/want to grant all privileges to a gm (he or she probably doesn't need drop, for example) for security purposes.
Of course, there's probably an option in a gui mysql admin program to set this up as well.