mmm , put all the suports (catwalk, wide suports etc.) to the selected segment and then, simply delete all the structure leaving the catwalks.
iam sure that this it work
go into individual setting for that segment, select whatever you want for that segment, then click OK and go to the autosupport generator and uncheck everything that you don't want on the other segments. Then generate the autosupports and the supports or catwalks will only show on the one segment you want.
You have to do individual settings for every segment. Make the indvidual settings for all the other segments nothing, just check off individual settings. Then put catwalks on the one like you did and go to global settings. Just go to generate final and it should work.