How can I change this php.ini setting when hosting a website with fortrabbit.com?

How can I change this php.ini setting when hosting a website with fortrabbit.com?

• Desired value: always_populate_raw_post_data = -1
• Hosting Plan: "Light"
• PHP Version 5.6 (Don't want to use PHP 7.x)

What I have tried

• fortrabbit.com Admininterface

  • Result: "always_populate_raw_post_data" is not configurable there

• Set php.ini values via .htaccess in Document Root

  • Result: 500 Server error

• Created a second php.ini in my documentroot with the desired value

  • Result #1: Nothing
  • Result #2: phpinfo() shows "none" in "Scan this dir for additional .ini files"
  • Result #3: phpinfo() shows "none" in "Additional .ini files parsed"

• Tried to edit the /etc/php/php.ini

  • Result: Could not save the file, I'm not root on this server

Why I would like this to work

• I want to run Typo3 7.6
• Typo3 install tool complains about the missing php.ini setting
• I like the features, that fortrabbit.com offers
• I'm not affiliated/payed by fortrabbit.com

I answer my own question:

Q: How can I change this php.ini setting when hosting a website with fortrabbit.com?

A: I cannot change this php.ini setting myself: always_populate_raw_post_data = -1. Had to ask support of fortrabbit.com. They did it for me.