Hi Wclear,
Instead of using Hex-editing, you can use Skwasjers exelent tool S3D, which can be downloaded here:
http://sh4.skwas.net/
That way you can later on continue the work without destroying the scene.dat (and it's allso easier to use) Dave was using Minitweaker in the begining of ROW, but found out that the scene.dat was very sensitive to editing that way and suddenly strange things started to happen in peoples game.