FWIW, I unchecked the TurboTax box that asked if I had a K-3. That way, I could get the Federal review completed and get e-filed. Then I printed out a copy of my K-3 and mailed it to the IRS - certified. Between the TurboTax folks and what I read on the IRS website it wasn't clear to me what to do, and the only way to get my return successfully reviewed and e-filed was to uncheck that box.
