How to build a digital map for a building?

I am required to build a digital indoor map for my school building. I need this to help provide indoor localization for the building. The map has to be in kml format.

I am not able to figure out a way to build the map digitally. All i can think of is draw/connect geo-codes that can shape the indoor plan in google earth.

If any body could share their opinions.. I would be grateful!!!

One option is to use a ground overlay within the maps api. Then you can create an image of your floor plan and then overlay it on your map. The corresponding KML element to use is GroundOverlay.

Have you checked out Google SketchUp? It allows you to model buildings, save as KML and display in Google Earth.