Revit :: Set Up Alternate Dimensions That Report Value Represented In Different Way Via Formula

is it possible (Revit 2014) to set up alternate dimensions that report the value represented in a different way via a simple formula? 
 
I am trying to show my dims as brick units (based on standard metric bricks 215x102.5x65mm with 10mm mortar joint), and was hoping to create new 3 dim types, based on CO+, CO- and CO, so the alternate dims i want would be:
 
CO+ =[value-10]/225CO- =[value+10]/225CO simply =[value/225] 

with the appropriate suffixes (CO+, CO- and CO). If this is possible..... or on the cards?