Edit multiple Cogo point elevations by specific distance

I am using MicroStation V8i (SS2) InRoads (SS2) and need to adjust some cogo points elevations by a specific distance.  For example, if I have a group of points with different elevations that I would like to raise or lower by 3" is there an easy way to do this?  I tried using Geometry---> Cogo Points---> Edit Multiple---> Reassign Elevation but, it seems that you can only assign a specific elevation, not a distance to change by.  At this time the way I am changing points is by exporting to excel, editing, and re-importing.  There should be a way to do this inside InRoads I would think...  Any help would be appriciated.

Thanks in advance,

Nate