Two notes sharing a beam with stems in opposite directions

Click the beam and drag it between the notes; use the handles to adjust the angle. Although it should be noted, this notation style isn't necessarily recommended anymore except in more extreme cases than that. I doubt any current (as opposed to 19th century) publisher would choose to do this for that particular example. So I'd recommend against doing this here if the goal is to have the music read by current (as opposed to 19th century) musicians :-)