This was the first year I overwintered mine indoors and surprisingly I did
I had mine in a pot last summer and kept them in the same pot over the
winter. When the leaves died, I cut them all back. Over the winter they
were kept near an east window and watered only when completely dry. The
room I kept them in is what I call my "bedroom greenhouse" because it's
where I keep all my overwintering plants as well as my orchids. It has a
supplemental "garage" style floresent fixture that is on 16 hours a day, a
humidifier and the room is probably kept around 65-67 degrees.
Sometime in February I noticed the callas starting to send up shoots so I
moved the planter directly under the light fixture and started watering a
little more frequently (didn't saturate the pot, but didn't let it get
completely dry). I've not got two completely unfurled leaves and many more
shoots coming up so have started fertilizing with some fish emulsion.
Don't know if this is the correct way to do it, but it worked for me.