load a lang file into an array

Hi!

Anyone who knows how I can populate an array with key/values from a lang file WITHOUT loading any from system first? I tried this:  

PHP Code:

$this->lang->load('some_file_lang','english'); 


If I var_dump $this->lang->language I will see an 'array' starting with the key/values from the system files, and then the ones from some_file_lang above. The system key/values are already the docs says. 
Any way to get an array from my own file only?