Whether this is possible or not, it would be good to add it to the website/documentation.

~ php -d zend_extension="/usr/lib/php/extensions/no-debug-non-zts-20131226/xdebug.so" -r 'echo ini_get("zend_extension");'
Cannot load Xdebug - extension already loaded
~

~ php -d xdebug.remote_enable=1 -d xdebug.remote_host=localhost -d xdebug.remote_port=9000 -d xdebug.remote_autostart=1 -r 'xdebug_break();'
~

It does not activate in the attached debugger on 9000 like it does with phpunit:
php -d xdebug.remote_enable=1 -d xdebug.remote_host=localhost -d xdebug.remote_port=9000 -d xdebug.remote_autostart=1 ./vendor/phpunit/phpunit/phpunit --bootstrap file.php tests/fileTest.php

Fyi, to add more keywords for searching, I want do debug code given on the command line (CLI), but it does not seem to trigger.

Sorry, I do not know, but this is not a support forum.