It appears that pattern Kwik Sew 2689 would also show how to do this type of strap.
Kwik Sew 2700 and possibly 3165
Kwik Sew 1615--discontinued
Kwik Sew's Swim & Actionwear book also has great directions and pics on how to do this. It also shows how to add contrasting binding to any style suit pattern. Which is basically what I have done in the past with the one shoulder suit.