TurboTax Online does not have the ability to manually edit any forms. All information has to be entered through the question-and-answer interview. It makes no difference whether you have paid for TurboTax or not.
The CD/Download TurboTax software has a forms mode that provides access to the forms. However, even in forms mode, no manual entries are permitted on Form 8582. All the information that is used to complete Form 8582 has to be entered under the individual passive activities, such as Schedule C, Schedule E, a Schedule K-1 worksheet, etc.