I'd think Computershare WOULD provide a 1099-B. Have you talked to them and asked why they didn't?
Even without a 1099-B you certainly can enter the sale in TurboTax, assuming you have all the needed information. Using the "Stocks, Mutual Funds, Bonds, Other" interview you'd tell TurboTas that you didn't get a 1099-B. You'll be placed in a slightly different interview - it's pretty much the old, old, TurboTax "step by step" interview from years back - and that interview will solicit the information it needs to report the sale.
But I think I'd first get in touch with Computersquare.
Tom Young