Setting up a key to cycle through editor modes

Hi all. I'm a longtime UE3 user, now diving into Unity. Something I very much miss about the UE3 editor is simply hitting the spacebar to cycle between the "move/rotate/scale" modes when I have an object selected. The "QWERTY" shortcuts for that are nice, but I'm still not entirely in muscle memory mode with them.

It seems feasible to replicate that with a simple editor script, but I'm concerned about creating input conflicts with something as common as the spacebar. The spacebar doesn't seem to be tied up with any other action with the scene view though.

So, specifically I'm asking if an editor function like that can be set up to only be active if a "scene" viewport is the active window?

Thanks for any hints you might have, it's very much appreciated!