How to change Apache PHP version (installed with homebrew) on OSX

[Zephilim]

I have installed php version 5.4 using homebrew (brew install homebrew/php/php54) and I can now use this version on the command line ok, which overrides the default installed version 5.5 which comes with OSX El-Capitan. Now I need to modify the apache config so that it too now runs 5.4 and not 5.5.38.

Now, established wisdom says that I should be modifying /private/etc/apache2/httpd.conf. So the line under question is:

169 LoadModule php5_module libexec/apache2/libphp5.so

but that libphp5.so, is rather general and doesn't look specific to either 5.4 or 5.5.

In another article I found https://www.euperia.com/development/using-different-php-versions-osx-apache-homebrew/1441

the httpd.conf file looks like this, where the appropriate line can be left uncommented according to specific php version you require for apache:
119
120 # LoadModule php5_module libexec/apache2/libphp5.so
121 # LoadModule php5_module /usr/local/Cellar/php53/5.3.29/libexec/apache2/libphp5.so
122 LoadModule php5_module /usr/local/Cellar/php54/5.4.36/libexec/apache2/libphp5.so
123 # LoadModule php5_module /usr/local/Cellar/php55/5.5.20/libexec/apache2/libphp5.so
124 # LoadModule php5_module /usr/local/Cellar/php56/5.6.4/libexec/apache2/libphp5.so
125

My installation of php54 by homebrew is located at /usr/local/Cellar/php54/5.4.45_6/ and when I run php --version I see:

$ php --version
PHP 5.4.45 (cli) (built: Oct  1 2016 22:20:59)
Copyright © 1997-2014 The PHP Group
Zend Engine v2.4.0, Copyright © 1998-2014 Zend Technologies

Under /usr/local/Cellar/php54/5.4.45_6/, I can't find any reference to libphp5.so so that I can configure an absolute path to it (so essentially, under ../5.445_6/ I can't see a libexec/.. which I'm expecting somewhere to contain a libphp5.so that can be referenced).

As a quick test, I configured it with /usr/local/Cellar/php54/5.4.45_6/libexec/apache2/libphp5.so, but since this file does exist, apache failed to start.

So my question clearly is, how do I find the correct path to the 5.4 version of PHP, so that I can configure apache to load the module correctly on start up, thanks.