You can do it right in the project window. Just select all tracks you want ALT+SHIFT and choose the bus you want in the Track Inspector, thats it. This is for Audio tracks.
For VSTi you can open Channel Settings window, then select all VSTi’s you want, go to Output in the upper section ALT+SHIFT and choos the bus you need - all your selected instruments will be assigned to that bus.
Or you can use MixConsole #2 or #3 for this purpose - just make certain settings to see routing only, make it as small as lower zone Mixer, put it over it and open when you need.