Add account lookup to mda object

I have identified multiple use cases for generating powerlists based on the data in one of our MDA objects.  However, I am unable to use this object because account lookup was not enabled when it was created.  Fortunately we do have the account id field included in the object but I am unable to establish the lookup link to the account object (not in the dropdown).  All assistance on solving this one is greatly appreciated, thanks!