Oh, Btw, is there a way to use multiple skillbars via sprites editing?
hmm...I don't believe it works that way. But all hope is not lost.
1. There is something called Battlemode Overlay written by Abraxa

I haven't tested it so I am not sure of the details. Check it out if you are interested.
http://dar-clan.de/igd/igd_v02_source.zip2. Wait for Renewal Client to be implemented on your server.

This was released from eAthena a few days ago.
Since 17 june 2009 KRO Sakexes will not be supported anymore by Gravity
I advise to use Sakexe_RE instead
Persisting in keeping on using sakexe will eventually result in sprite errors, gravity errors when more content will be added to the branches.
So, I believe sooner or later, servers will shift to the Renewal Client and you will be able to enjoy the new user interface including a 4th Skill Bar.