hi Benjamin,
I've been playing with Personas3 for at least a couple days now, and I believe it's possible - but not a 'straight forward' way of doing such.
since Personas3 works with html/js you can always use and delegate the 'view' to the upper UI5 component (Personas3 is pretty much a UI5 application) - so you would construct all your screen elements using scripts inside personas and adding them into the user content area.
I'm not too sure how SAP developed the screen Michael linked in that document above (page 25) - but unless I'm doing something pretty wrong, there is no such way to embed UI5 directly in a personas flavor.
Cheers,
D.