You can look up Exception 2 for Form 8949 on IRS website. Technically the requirement is to report sales with adjustment on "an attached statement containing all the same information as Parts I and II and in a similar format" as form 8949, but 1099-B seems to work. When you elected to only put in summary of sales instead of importing/typing individual sales, Turbotax will give you instruction to print form 8453 and mail it with your 1099-B - doesn't seem like Turbotax support attaching 1099-B electronically yet.
