PHP6 is dead, long live PHP6!
Assuming you are in your sources folder, just run
docker run -v $PWD:/var/www/html -p 8080:80 wizaplace/php-6-apache
Now, you can play with PHP6 here: http://localhost:8080/
The image is available on Docker Hub: wizaplace/php-6-apache
docker pull wizaplace/php-6-apache