First read this
Everyone say that is only posible in vsro because there is a limit of time that u can get xp....BUT....actually that is in csro too. If your account have a cid with age below 18 years you will have xp limit too...like 5h or so...
So...if you change the cid of the plvl chars you will have xp limit, fight until the limit is done, then go plvl...it should work. And for farming add some lv1-9 chars to reduce the average level of the party.
I think it should work...but... can anyone try this and confirm?