Found a clean way to do it within Turbotax 1040 within Investment Sales topic, implementing 2016 Instructions for Form 8949. Enter a summary for a sales category (short or long term), fill in amounts, check the adjustments box, then type code "N" in the box for adjustments, click done. Next screen shows Gain/(Loss) zeroed out. (You can read the "mailing instructions at this point" - Box A and Box D sales may not need Form 8453 since Code "N" is so specific.) But be sure to look for Form 8949 which has just been created by TurboTax: gain/Loss zero.
