An old post, it is mentioned by some that answering to these is not appropiate....

But being a real planner I think I know better.. :)

To use the excel way to update: 

An activity’s percent complete can be calculated according to activity duration, activity units, or a physical percent complete that you enter for each activity.

Choose Project, Activities, and display the Activity Details General tab or add a column for 'Percent Complete Type' in the Activity Table. In the Activities window, select the activity to update and display the Activity Details Status tab. .In the Activities window, select the activity to update and display the Activity Details Status tab. In the Activities window, select the activity to update and display the Activity Details Status tab. In the Activities window, select the activity to update and display the Activity Details Status tab.       

If the selected activity’s percent complete type is set to Physical, you can enter its physical percent complete in the Physical % field.

To edit the Physical % field, the activity must have started.
Enter the physical percent complete and the remaining duration for the activity.

If resources are assigned, you must also update each resource’s actual regular units.

 Cheers
 

I am also still lokking for an anwer to this post.

Regrads

Bijoy. K