I'd like to second this by suggesting the docs include a recommendation on how to incorporate this within an existing React app. Apologies if this is available within the Yeoman generator but if so it wasn't obvious from the docs.

FWIW, I've found the isomorphic render examples within the Megaboilerplate examples for React [0] to be instructive.

[0] https://news.ycombinator.com/item?id=11861926