Slate render to texture

I was wondering what the better approach would be to render a Slate UI on a texture, for use in animating menu screens in 3D.

I guess it would be to create an off-screen viewport maybe, and use it instead of GEngine->GameViewport to call AddViewportWidgetContent, but then I’m not sure I can do that yet, and if I’d have to manually transform mouse events from the game viewport into that viewport (probably).

Did anyone do this?