How to change cameras from external input during sequence?

My sequence that runs during the main menu has multiple cameras and is also responsible for handling animations/etc within the 3D menu environment.

I don’t want the sequence to change the camera using the camera cuts, I want to do that externally when the player goes to a different part of the menu (eg. Character Selection). And of course they should blend.

However, I can’t see any functionality to change the active camera that sequencer is looking through. I’m sure this isn’t intended usage anyway, so what would be the correct way to achieve this?