I made this video to show how to do a rough CVL conversion in the demo, including a very simple deck & superstucture.
www.youtube.com/watch?v=eG22xE7jvIY1:18 onwards shows editing the overhead view
In short;
1) Click on the St1 box, move cursor over the ship to reset that line
2) Repeat for St2-St6
3) Click on the X next to the funnels, hit yes to reset them
4) Select St1, make sure 'Assymetric Superstructure' is unticked
5) Draw a rough deck on the left side of the ship picture, clicking places a point, right click ends drawing, 's' snaps in 45 degree increments to near your cursor, and 'd' undoes the last point
6) Repeat for any other symmetrical structures (lifts, etc)
7) Tick 'Assymetric Superstructure', repeat for island, etc. In this mode you can draw on either side of the ship
8) Tick 'Assymetric Funnels', click the '...' in the funnel list, and click to place them
A general note is that the St1-St6 parts are layered, with St2 on top of St1, etc.