Report the distributions as you would any distribution from an IRA by entering the Form 1099-R under Wages & Income -> Retirement Plans and Social Security -> IRA, 401(k), Pension Plan Withdrawals (1099-R) and answering the follow-up questions.  Be sure to click the Continue button on the Your 1099-R Entries page and enter the amount qualifying for the particular 72(t) exception that applies.