I could tell you how to modify this directly in the database.... but... but... since I've never used this "cluster" option, I really don't know what CMOD is doing in the background... meaning, that even if I give the way to do it... most probably that won't be enough, since some other actions needs to be done.
And I have no clue what kind of actions are needed... so I prefer not to tell you how to switch the flag from off to on...
Maybe in that case, it would be good to open a PMR, and explain your problem. Maybe the support will be able to help you to figure out, how to solve your problem.
Sorry, cannot do more than that....