Change Command_R to Shift+Alt
There are some errors in your private.xml like SHIFT_L/OPTION_L are no KeyCodes but ModifierFlags. The | to link the 2 modifiers was just guessing (and luck).

Use this xml snippet instead:

&lt;?xml version="1.0"?&gt;
&lt;root&gt;
    &lt;item&gt;
        &lt;name&gt;Change Right Command Key to Shift Alt&lt;/name&gt;
        &lt;identifier&gt;private.right_command_to_shift_alt&lt;/identifier&gt;
        &lt;autogen&gt;
            __KeyToKey__ 
            KeyCode::KEY_8, ModifierFlag::COMMAND_R, 
            KeyCode::KEY_8, ModifierFlag::SHIFT_L | ModifierFlag::OPTION_L
        &lt;/autogen&gt;
        &lt;autogen&gt;
            __KeyToKey__ 
            KeyCode::KEY_9, ModifierFlag::COMMAND_R, 
            KeyCode::KEY_9, ModifierFlag::SHIFT_L | ModifierFlag::OPTION_L
        &lt;/autogen&gt;
    &lt;/item&gt;
&lt;/root&gt;


Tested with a german keyboard, danish keyboard layout, Mac OS X 10.7 and KeyRemap4MacBook:

{}{}{}{} :-}


Please don't forget to reload the xml in the Change Key tab in Karabiner/KeyRemap4MacBook (that's the same but different named app for Mac OS X &lt; 10.9) after applying the changes in the private.xml.