Wouldn't be too hard, but it would take a while to get it right.
You can do it by pressing shift+u (and then you might have to press the spacebar...) and start placing obects (barriers/cones/chalk marks etc.) You'll have to keep on looking at the image and look at the objects you placed in LFS (with the helicoper view) to make sure everything looks right...
I'd recomend the 8-lane dragstrip rather than the autocross area.
True mate, but sadly we've got to make the best use of the stuff thats given... you can either make a miniturized version on the 8-lane drag strip or go for the autocross area and make use of the L shape. You would loose the straight (somewhat) but at least you probably would be able to keep the scale realistic...
About using the image to make the layout... Get in touch with Flame CZE he made the LFS Layout Viewer (It would give a graphical output of the layout you made.) He would be the best to comment on your issue.
The Layout Viewer would be useful for you to match the layout to the image (set a few basic points, generate the view and match with your image. Edit/alter and go into more detail... )
Not sure if the Viewer is available to download at the moment, if its not get in touch with Flame... Good luck!
I'm sorry, the layout viewer is not avaliable at the moment. I'll try to make an update to it as soon as possible and place it it the LFS Layouts DB server to use. I'll let you know
If you have an image editor with layers, you could take the AU1 background from this, overlay the layout you want, load it up in aforementioned program, and use it as a template.
That whole track should fit entirely to scale on the autocross area. On the google map view that was posted, it appears to be roughly 150 meters by 400 meters. The autocross area is bigger than that. The short L leg would be extra empty space that could be used for something else.
