Disney financing is treated as a mortgage. You may be able to deduct the mortgage interest. You should contact a qualified tax professional to be certain.
Assuming you don't have a second home mortgage elsewhere possibly. The timeshare must secure the actual loan so if you financed some other way, you can't write off under the second home option. The question I'm not sure about is whether DVC actually writes this as a mortgage or a consumer loan and it's important to the answer in this situation.
You will get a 1098 from DVC, just like your primary mortgage lender. In most situations it is tax deductible but consult your tax advisor about your particular situation.