This has not yet been implemented in 2020 TurboTax. When implemented, you can expect it to behave similarly to the way the reporting of hurricane and wildfire disaster distributions was done in the past.
If you plan on spreading the income over 3 years, for estimated-tax planning purposes you could try entering a code 2 Form 1099-R for a distribution of 1/3 of the actual amount of the distribution. (The maximum CRD is $100,000, so any actual amount distributed beyond $100,000 that would need to be entered separately with code 1). This form will have the amount in boxes 1 and 2a, box 2b Taxable amount not determined marked, code 2 in box 7, the IRA/SEP/SIMPLE box marked, and any taxes withheld in the boxes for federal and state tax withholding.
