Xcode 4 Custom Key Commands - Add to IDETextKeyBindingsSet.plist

gistfile1.xml

    <key>GDI Commands</key>
    <dict>
      	<key>GDI Duplicate Current Line</key>
      	<string>selectLine:, copy:, moveToEndOfLine:, insertNewLine:, moveToBeginningOfLine:, paste:, moveUp:, moveToEndOfLine:</string>
      	<key>GDI Delete Current Line</key>
      	<string>moveToEndOfLine:, deleteToBeginningOfLine:, deleteBackward:, moveDown:, moveToEndOfLine:</string>
      	<key>GDI Move Current Line Up</key>
      	<string>selectLine:, cut:, moveUp:, moveToBeginningOfLine:, insertNewLine:, paste:, moveBackward:</string>
      	<key>GDI Move Current Line Down</key>
      	<string>selectLine:, cut:, moveDown:, moveToBeginningOfLine:, insertNewLine:, paste:, moveBackward:</string>
      	<key>GDI Insert Line Above</key>
      	<string>moveUp:, moveToEndOfLine:, insertNewline:</string>
      	<key>GDI Insert Line Below</key>
      	<string>moveToEndOfLine:, insertNewline:</string>
    </dict>

Find:
/Applications/Xcode.app/Contents/Frameworks/IDEKit.framework/Versions/A/Resources/IDETextKeyBindingSet.plist

Add this dictionary to the PLIST and then go into Xcode -> Preferences -> Key Bindings and add custom key bindings for these commands. Done!

Great! I seek for these hot keys for months, it helps me a lot!
Thx very much, @gdavis !!