K, i'll do my best. So when you use the auto support generator, it automatically put in catwalks for you if you don't uncheck it. You can remove those catwalks and use those as the building material. To make sure you don't have overlapping supports, you may want to make use of the individual auto support settings for certain track pieces.
Look at my dev page. I made use of the individual settings by turning off all of the catwalks/supports on the track. Then I used a specific track piece, turned the catwalks back on, re generated the catwalk support, then removed the catwalks from the track.
http://www.nolimitsdevcenter.net/p5694
(you will notice that there aren't catwalks anywhere on the track yet, that was individual settings at work)
If you need more catwalks, make sure you uncheck the clear previous strcuture box because then everything will dissappear.
It is kinda confusing but just mess around and you will get it in a day or two.
You can also make wooden support structures, they look nice also.