There is another way I wasn't aware last time. All what need to be done is adding key binding in the *.vsct file. This will register your key shortcut and bind it to the selected command.
<KeyBindings>
<KeyBinding guid="guidSomehingCmdSet" id="cmdidSomehing" editor="guidVSStd97" mod1="Control" mod2="Control" key1="T" key2="S" />
</KeyBindings>