It is manually changing the information in the file that tell the editor things like, where the model is, where the textures are and what one to use, weather it is static or dynamic. the script file to use if dynamic, things that the editor needs to know about how to display the model.
The other method is to use the model importer... in the file menu in the editor.
Instruction are given in the guide posted here: http://steamcommunity.com/sharedfiles/filedetails/?id=399300304
Not a hard task, just tedious, If you have all the models pack from all prior version that is a lot of media to convert. but you can use your existing media this way.
Hope that answers your question, Thanks
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