That's still a 3d model, Erika. I believe Christaline just wants to view the 2d linework as an axon.
I think there maybe a way to do it, but I haven't tried it myself!
Save each of the 2d floor plans as objects as described by this wiki article
here. Open a new empty ArchiCAD file and place each floor 'object' onto a separate storey. Use trace and reference to align them over the top of each other. Set the 3d window to Axonometric mode and view the plans from the required direction. Adjust the storey heights so the plans do not visually overlap. Now save this as a 3d document and annotate.
Post a screen shot if it works!