If you only have outside as an option (no unheated cellar bulkhead or unheated garage that gets cold enough), you can pot up in individual plastic pots and put outside under a thick layer of bark mulch. I would plant in plastic round bulb pots that can fit in your window boxes or other suitable container. Use plastic for obvious reasons. You can get these bulb pots relatively inexpensively at nurseries in several sizes. These pots are more shallow and squat than regular pots. Then pot in groups of 5 or 7 or 9 depending on the pot size and variety. You can then bring up and put in the window boxes or bring inside at the appropriate time from under the bark mulch. I think the 6 packs would be too small to pot up successfully and remember plants look better when planted in odd number groups. Also they would be hard to prevent from freezing solid through. It would be too cumbersome to deal with the individual bulbs too.

Here is a link that might be useful: Ehow - bulbs in pots