My friends had a wedding a few years back where most of the men were wearing small wrapps and a piece of same-tartan fabric over the sholder that sounds a bit like this.

I think they folded pleats into the shoulder fabric at the shoulder and tucked the ends under the belt and kilt. The back of this shoulder plaid was spread out from the pleating so that it wrapped around the sides a bit like a cape tucked into the back of the kilt and only over one shoulder.

This was all costume, though. I didn't wear one because I was dressed in a leine-like tunic as a hermit.