The interest you pay on a timeshare loan may be deductible as an itemized deduction on your tax return, but only if you borrowed against your primary home or the loan uses your deeded timeshare week as security or collateral for the loan.
Also, if you pay any property taxes on your timeshare, they may be deductible as an itemized deduction.
You enter mortgage interest or property taxes in the Deductions and Credits section of TurboTax, then Your Home and then Mortgage Interest and/or Property Taxes.