It works exactly the same way. In fact, the aid is called the same.
However, with contact an indirect rein of opposition is merely brought across and over the withers so that there is a direct line from that rein to the opposite hind leg. No need to raise it under normal circumstances. Though you could raise it if you need to adjust the neck.
I have never heard that you should ever cross your rein over the withers...
OP I personally would not use spurs on a greenie, I think spurs are for refinement in advanced movements only. But if you and your trainer think its the right thing for you and your horse, I wont tell you that you can't.