Hi ,
What I read was that you can duplicate all the native tabs in a custom group , execute the Hide Command Labels action on this custom group , and then hide the native group ; see if this works.
Another option is as follows ( copied from Microsoft® Excel® 2010 Inside Out
By Mark Dodge, Craig Stinson ) :
To hide command labels , right click the Ribbon , click Customize The Ribbon , then right click any Custom Group in the outline , and click Hide Command Labels. Note that this command appears on the shortcut menu , only when you click a Custom Group.
Narayan