Fortunately, the wonderful, brilliant castor solved all those "I'm not familiar with [some program]" complaints with his genius tool, Shaiya Studio!
Just go here
and follow the directions CLOSELY, mind you. You'll be able to access and edit almost all server files visually, including all maps/portals.
Once it's installed and configured correctly, go to ShaiyaServer > SERVER > PSM_Client > Bin > Data > Map > 47.svmap (since the portal to get into OI is located in Jungle). Map 50 is GRB, so open 50.svmap to change the 60 portal there. Then save and of course, restart the server.
Good luck!