You can still follow these guidelines below, however Jack Skinner has posted up an easier way to install PHP7 using homebrew here:
Note: you can also use this process to install PHP7 just as easily and avoid the gotchas at the end.
If, like me, you are keen to work with the latest PHP syntax on the latest Mac OS operating system — and especially if you are trying to keep up with the rapidly moving world of Laravel development — you will have noticed that there have been some recent changes that make this more difficult.
Cotswolds-based web developer digs Laravel, CodeIgniter, PHP, jQuery & MySQL. Makes a living cutting code into tiny bits.