Update: we’ve published the install guide here: https://msdn.microsoft.com/en-us/Library/vs/alm/TFS/setup/overview. Feel free to post comments or questions on that here as well as leaving feedback directly on the MSDN page.
We’re wrapping up work on a new install guide for TFS 2015. Here’s what we have for a dual server configuration. If you use it and run in to trouble or just want to comment on it, post a comment here.