I've put on my great kilt by the "laying out and pleating method". Quite a few years back I was taught a style that consists of holding the top edge of the plaid in your hand and gathering it into pleats. Then you drape it over your left shoulder, hold it in place with your chin, and belt it on, bringing the aprons around in front of you and then adjusting the rest of the kilt to your satisfaction. The gent that taught me this method stated that the great kilt was a way to wrap 5 or 6 yards of wool around you for warmth, and not look like a bag of rags "from the front".
I've also been told, but I'll have to look for documentation or sources, that there is evidence of both belt loops, and even small metal rings being sewn into the plaid.