It does not need light during dormancy, mine go in the fridge for the fall/winter.
In zip lock bags.

Use rainwater or distilled water ONLY, no tap or bottled waters.

I'd slowly get it used to outside temps then when it gets close to freezing put it somewhere like a basement or garage where the temps stay around 35-40 F.

Hi LunR,
What are your climate conditions like? VFTs can handle light freezing lemps over the winter. If it is possible to left them go dormant outside, that is the best approach IMO. If it is too warm where you are at than the fridge trick does work. If folliage remains on the plant and does not die off completely, make sure it gets light, other than that, as stated, light is not really necessary. (If there are no leaves then light wont do much good afterall) Is this the first year you have had it? If you recieved it bare root and/or it is not fully acclimated yet then the argument could be made that allowing it to skip dormancy this season is beneficial. Personally, I often skip dormany my first year with a new VFT and allow it to focus on vegetative growth. I only do that first season, especially if it is recieve bare root.