I don't know about the climate at your home, but gunnera are usually considered hardy only to about USDA zone 8a (minimum winter temps to 10-15 degrees F). In zone 8, the gunnera will die back completely in winter and will require protection for the crown. In colder areas, it is suggested to grow the plant in a greenhouse.

I also checked out a number of websites and found specific instructions NOT to plant new plants this late in the season.

Isn't this going to be a difficult plant to over winter in the house as opposed to a greenhouse environment? I'd think that it will be difficult to supply enough humidity for this plant.

Here is a link that might be useful: Gunnera link