Comment 19 for bug 965921

"How can I create a custom shortcut for launching a terminal in GNOME Shell and 12.04?"

Just create it in the 'Shortcuts > Custom Shortcuts'. You can't just use "Insert", it needs a modifier like Ctrl, Alt, ect.

*If you want to use Super that usually requires a little work . Ex. - Super+Insert
Set it first in the above Shortcuts > Custom Shortcuts
Then open gconf-editor > /desktop/gnome/keybindings/custom*
In the binding key change the <Super> to <Mod4>, ie. <Mod4>Insert