You will enter it in the same area you would a normal Form 1099-R. However, your form might have line numbers instead of box numbers. Read it carefully when entering the information to make sure they numbers are placed correctly.
To get to that area in TurboTax:
While inside the software and working on your return, type 1099-r in the Search at the top of the screen (you may see a magnifying glass there). There will be a popup that says Jump to 1099-r. Select that to get to the general area. Then, select that you will type it in yourself.