I used both the Lansinoh and Gerber bags. I bought plastic shoeboxes from the Container Store. I put 4 oz in each bag and sealed the bags after marking the date and laid them flat to freeze so they froze into a nice card shape. Then I stored the bags on their sides in the boxes with the lid on (so nothing was set on top, because the sides of the bags would get splits in them otherwise). I kept them in order by date so I could use the oldest milk first. As I accumulated a stash, I stacked the boxes in the freezer by order of date too. One plastic shoebox can hold about twenty 4-oz bags, 80 oz.
Because the thawed milk has to be used in 24 hours and our son didn't always use all the milk I sent and I didn't want it wasted, I only sent one or two bottles of thawed milk each day and the rest I sent was fresh from pumping the day before so it could be sent back the next day if it wasn't used. I used masking tape for labels and numbered the prepared bottles in the order they were to be used, and the thawed milk bottles were always the first ones to be used.
Each day's pumped milk went to make up a few fresh bottles for the next day and I froze the rest.
For more support, there is a Yahoo group called BFWorkingMoms. Good luck !