Bootsy's Lady Banksia Rose Bush

In my mother-in-law's yard is a beautiful, huge Lady Banksia rose bush. It is about 20 years old and has been left to its own devices for much of that time. It is as big as a mid-sized SUV and produces tons of pretty yellow flowers. I would love to root a piece to this bush, or in some other way reproduce it, for my own yard, but I don't know how to go about it. Any suggestions?
Bootsy's Lady Banksia Rose Bush
Originally uploaded by Carolina Victory Gardener