Hello AmyC,
this question is not related to how lump sum distributions are handled (Form 4972) but how to invoke an option to report another value on Line 18 (per IRS guidelines) of Form 1116 - by using the Worksheet provided in the IRS instructions.
From the responses to this question to date it appears that TurboTax does not support this function. That's OK, as it is only an option, and for many people it is probably not an issue. However, people just need to be aware of this so that they can assess for themselves if they want to use a different tool for reporting their taxes.
