You enter these into TurboTax by entering the W-2 itself. Amounts in box 12 of your W-2 are to be entered only in box 12 of TurboTax's W-2 form. The only effect these might have on your tax return is that they can result if a Retirement Savings Contributions Credit if you qualify.
As VolvoGirl implied, these are not IRA contributions, so don't enter the box 12 amounts anywhere under Deductions & Credits.
