"Can integrative negotiation be effective when parties have unequal power?"

Yes ofcourse, 

As you will have a list of priorities and they will be sorted by most important..

Each main priority can be revised in a way to get feedback.

No matter how powerful the other party is, in any negotiation both parties are meant to finish the deal satisfied 

This scenario has been visualized from the less power party perspective.

I.E : If you have5 on the list ,worst case scenario1 out of5 will work 

Yes, if they all share the same vision and i can do mentality, power is subjected to submission.

Yes, it can be effective when people have unequal power.  Priorities are sorted out as of the importance, main priority can be revised to get feedback, negotiation can be dealt with to get satisfied results, whatever the situation.  It has to be visualised from the less powerful party perspective.  Atleast one out of five will work out from a list of five.

Hence integrative negotiation works and is effective.

Sometimes it can yet it is not good to have two meetings with unequal powers.  Everthing has to be defined from the beginning, how many are meeting, what positions, etc.