Download the modified CUI file from

Copy the unzipped acetmain.cui file to your AutoCAD support folder (making a backup copy of the original version) - e.g.:
C:\Documents and Settings\YOURNAME\Application Data\Autodesk\AutoCAD 2009\R17.2\enu\Support (WinXP)
or
C:\Users\YOURNAME\AppData\Roaming\Autodesk\AutoCAD 2009\R17.2\enu\Support (Vista)

Run AutoCAD 2009 and start the CUI command

In the top left panel, switch to the current workspace, so that its contents is displayed in the right panel:

Click on the "Customize Workspace" button (turns blue)

In the left panel, expand the tree "Partial CUI files" > EXPRESS

Check the box by the "Ribbon Tabs" item

In the top right panel, click the "Done" button and end the CUI dialog with OK