For the last 12 years I have used Sibelius with a Yamaha electronic piano keyboard at the side of my computer at 90 degrees to the desk. Its not the most convenient way to have things, but I get by!
I notice many users have the piano keyboard across the front and some have them that can pull out from under when not in use, often custom made.
Has anyone found any off the shelf computer desks that are suitable for this type of arrangement that they are able to suggest.#