Enter the 1099-B as it reads on TurboTax's default 1099-B entry form, then click the blue "Guide me step by step" button.
Select the ""My sale involves one of these uncommon situations" option and then tell TurboTax you sold "Stock".
Start clicking through the subsequent pages (presumably everything's already filled in) until you come to the "Some Questions About Your Stock" page where you'll answer Yes, Yes and No to the three questions that come up.
You then enter the number of shares sold in the trade you're reporting on the "How Many Shares Did You Sell" page and then enter the number of "replacement shares" you owned after the trade, the shares bought in the +/- 30 days window.
TurboTax will calculate the wash sale loss disallowed number.
Tom Young
