I beleive this is true, but no longer works after Requiem 3.0 came out. The way it was done is like this:
On the day of maintenance, you place any items for sale, not just xeons for a period of 3 days. You would do it about 5-10 min before server shuts down, and then logout. When you log back in, you end up with having everything in your inventory back, yet the items that you placed in action still there. So you just cancel, and get the duplicates back. I'm sure there is now another way of doing it.