Install OpenCV and Facedetect PHP wrapper on production server

I have a CentOS server hosted on an AWS EC2 instance, that I need to install OpenCV and the PHP Facedetect wrapper.

The end result is that I want to be able to use a PHP script to parse an image, and output coordinates of various facial features, as described here:

https://www.xarg.org/project/php-facedetect/


I have managed to install OpenCV (I think) but am having problems finalising the Facedetect installation.

I am not particularly well versed in server admin myself so am basically muddling around. I will note, this is a production server, so the utmost care must be taken. I will of course perform a full backup prior to giving access credentials but if I need to restore from backup this would be a very poor result...

It is not necessary that you are familiar with the exact software mentioned above, but you must absolutely be fluent in Linux, ideally, specifically, CentOS and the process of installing PHP applications such as the one mentioned via command line. If any of what I have said is confusing to you please do not apply.

I think this should be a simple job for someone who actually knows what they are doing, which I don't! Thank you in an advance for your time.