I don't see how you can do the entry with the online version since the entry can't be made on line 20 without using an override. The online version does not permit overrides. (The online version uses the same underlying calculation engine as does the CD/download version. Only the step-by-step mode interface is different and only in some areas.)
The TurboTax help that suggests preparing Form 8606 manually does not really work since the result of a manually prepared Form 8606 will not be propagated to Form 1040. You would have to manually prepare your entire tax return, so what would be the point of using TurboTax at all. Using the override in forms mode of the CD/download version does propagate the result to Form 1040.
