The new short answer is yes: brew any-tap has been merged into brew tap so any repository, including private GitHub ones should now be supported.

brew tap restricts users to GitHub and checks for private repos. I created brew any-tap to support a wider variety of taps.

With very small changes (and no extra flags!), this PR brings any-tap to brew.

Users can use brew tap with GitHub as they always have or add one extra argument and tap any repository of any type from anywhere.

tl;dr

brew tap user/name # Same as it ever was

brew tap user/name URL # Tap URL, whatever it happens to be