While in the Report environment it is possible to convert the text to an Outline by using the "To Outline" choice from the Text menu but it is NOT possible to make a Model Style from the resulting Outline. This is indicated by the grayed out Add button in Model Styles.
Explanation:
The Report environment is not a Model. However, it is possible to create an Outline Model in the Report environment and then save it as a Model Style.
Solution:
Use Stationery instead.