This seems like a great assignment. I think it would be most interesting if you wrote a death speech in the voice of Caesar himself. In this way, we can get at the intent of the man and even have some interaction with the people who put him to death. You can make his speech incredibly creative. Let me give you two examples.
First, you can run with the theme of tyranny. Perhaps you can vindicate Brutus's actions. Now in death, Caesar might be able to confess that ambition, greed, and desire for more power got the best of him.
Second, you can work off of Anthony's speech and you can say just the opposite. You can have Caesar confess his pure motive and generosity. In this way, Caesar was not overstepping at all.
With some more thought, there will be other creative ideas.