It appears you need to convert to the TurboTax CD/Download version to add this page and election to the tax return. You may have to mail your return to make this election.
Once you do that, you go to Forms (upper left) then click Open Form on left to add the 4684 worksheet, next again Open Form and add 4684 page 4. Each time you will be asked to name your form which can simply be the disaster. Once loaded you will be able to make the appropriate entries in Section D.
You could also print off a Form 4684, complete that section and mail your tax return with that attachment included. Follow the Form 4684 Instructions