I wouldn't roll a kilt for storage. Any fabric has "memory" and will conform to the shape of what it's stored in.

I used to use safety pins to keep my kilt on a standard wire hanger, but have recently discovered a sturdy hanger from "order of the gael" that is designed just for kilts. It's wooden, with three bars on the bottom, each with two clips. The clip and bar arrangement allows for each apron and the rear to be sturdily kept in place, in a regular suit bag, in the back of my closet.

http://www.orderofthegael.org/kilthanger.htm