I don't know if this is on purpose, but the "Cmd+Shift+K" binding is not activated by "Ctrl+Shift+K" or "Alt+Shift+K" on non-Macs. Seems to work great otherwise, though.
If you really do want fine-grained control, for example, so that Cmd works on OS X, but it maps to something else entirely on other platforms, you can still use Ctrl and Cmd.