PEX ladder possible with RP server?

I was wondering if it is possible to set up the ladder with a role-playing server. I have done the classes using PEX, but the class system is fairly intricate.

For example, we have a base class (the first class members have upon joining), and once they meet certain criteria through mcmmo, they can rank up to a new class depending on what skills they have focused on. So if they went for more combat-type skills, they would level up into the combat-type part of the class system. Basically, lots of things branch off of the base class.

I was hoping to use this plugin, called Mcmmo Auto-Promote, in order for them to level up. However, it states that a ladder system must be used, and I was curious as to whether or not such a thing could be pulled off with a role-playing set-up.

Thanks in advance.