We have 2 product types - wine and corkscrews. We wish to ship Wine in it's own package in quantities of 6 per box.
Under Catalog->Manage Shipping Boxes set up a box called "Wine" with "Quantity per box" set to 6. Set height, width, length at 0 (unless want to put dimensions in).
For each wine product listing assign the Wine box under the Shipping tab.
If I have 8 bottles of mixed wine in the cart and 3 corkscrews then shipping will be calculated at three packages - one package of 6 bottles of wine, one of 2 bottles of wine, and one of 3 corkscrews