The Stage Storage Extension provided to subscription users uses feet and cubic feet as the units it shows. Since the program just does basic arithmetic and doesn't change the units it is fairly easy to change it over to metric.
The first step is to load the report using vbaload from the command line. The vba program is located at:
C:\ProgramData\Autodesk\C3D 2009\enu\Data\Reports\vba\SST.dvb (at least in Vista)
Next we need to look for all of the instance of ft or feet and change them to m or meter. To do this go to Edit menu and choose Replace. In the dialog enter in the find what box ft and in the replace box m. Press the find next button to find all of the instance of ft to replace with m. Make sure you use the Replace and Find Next buttons to select the instances that show up in the report. Next do the same, only using feet and meter instead. Now all of the output should be in the correct units.
Next we need to modify the dialog boxes. To do this expand the forms folder as shown in the picture below and double click on the UserForm1 and then change the Contour Area to the correct units.
This is the quick and easy way to do it. If you wanted you could have it read the units from the drawing and automatically use the correct units, but that's a little more complicated than what can fit in this post.