Hi. You are exactly right. But some notes:
1. Anything from include/internal are not auto-generated and you must track changes manually.
2. To simplify step 6 use next workflow:
2.1. on current version run gen-cef3.cmd. you obtain Classes.Handlers.tmpl and Classes.Proxies.tmpl folders. Move this folders for later usage.
2.2. Update CefGlue.Interop.Gen\include as you describe in step 4 (don't forget remove .svn folder).
2.3. now run gen-cef3 and compare newly created Classes.Handlers.tmpl and Classes.Proxies.tmpl with stored in 2.1. step. Now you can move changes manually to CefGlue.
If new files added gen-cef3 - you must include them in csproj manually. New files created if new cef interface (class) added.