Is Anyone Cost-Loading Schedules without using Units?

I am cost-loading and manpower-loading a schedule currently.  One of my resources will be a "material" resource, i.e., $ only.  When I enter a budget $ value and not enter a "units" value, P6 will not update the actual $ when I input % complete (duration % complete).  I was told by two P6 techs that I must use the units field to generate a cost value (and have "calculate costs from units" ON) in order for P6 to automatically update actual cost $ when % complete is input.  I also need the period values to calculate correctly for reporting. 

The only way I see where I input only a cost $ value and get P6 to calculate the actual costs is to use global changes.  Otherwise, I will be inputting material and labor resources items.  The only thing that muddies up my activity is that I use units as manhours.  There is no other field available.  I'm thinking of adding an idea for a future enhancement to give users some wiggle room on using costs without inputting a unit value.  My problem is there is no logical tie between units and costs for my projects.