Unusual chord input question (Sibelius 7 Vertical input problem)

I'm scoring a project in Sib7 where I need to input thousands of chords in whole notes using grand staff (piano) notation with a MIDI keyboard. Many of the chords are physically impossible to play at the piano with two hands because of the vertical spacing of the notes (think C1-C4-E5-G6 for a simple example.) The score is meant to be a representation of possibilities, and not for performance.

I'm wondering if anybody knows of a way for me to input vertically using a MIDI keyboard. What I want to be able to do is specify that I want whole notes, then play individual notes to be entered on top of each other from the bass up, in the same measure, on the same beat, in order to create chords vertically, then move to the next measure for a new chord.

The keyboard shortcuts for this process are very clear and I started out this way, but found out that this is an extremely time-consuming way of doing this. I'm really hoping that somebody knows a way to make this possible with a MIDI keyboard without having to revert to a thousand computer keyboard strokes to reposition the metric position of the note input.

I tried messing around with the flex time settings, tried using duration before pitch, and even tried messing around with 4 part scores and reduction/arrange settings, but the goal is to reduce keystrokes and increase efficiency.

I got really excited for a moment with duration before pitch, but then realized that it would still only let me specify pitches that I could physically play at the same time. I need to be able to play one note, then another in a vastly different register and have them grouped together as the same chord on the same beat.

Thanks!