Revit 2012 Silently Install Extensions

1. Extract REX setup from exe to C:\Autodesk
2. Go to C:\Autodesk\REX_RST_2012\x64\REX_RST\ (for x64)
3. Run the command as an Administrator: REX_RST.msi /q

via
Revit 2012: Silently Install Extensions - Up and Ready

http://upandready.typepad.com/up_and_ready/