As I understood the Imirie method of using Italians to get extra drawn comb, you put a medium of foundation on top of the box your queen is laying in, they will then draw out that comb and the queen will move up into it and start laying there. Then you place another med. of foundation on top of that and once the brood is finished emerging from the frames on the bottom medium, you can remove, freeze and store them.
I have read other's simply replacing drawn frames in the brood box with foundation and moving those brood frames above a queen exluder to let them finish rearing the brood on that frame without laying more.
I don't know which method is better, but I'm going to try the first method (namely because I don't intend to use a queen excluder for the first year, as any honey produced I'll be leaving for them.