Posting to Steam is easy. So: you've got your app, your build, your depot, your package, and your bundle. If you want to push a test build, just make sure the "developer comp" package for your app contains a new depot not included in the "store + CD-key" package. Then it's just a matter of writing a vdf file with appropriate app and depot numbers, and passing that through the Steam command-line. Alternatively, make a new password-protected app branch and push a build containing the appropriate depots to that.
If you get a step wrong, Persona 5 Tactica comes out 1 week early.
