Epiphany : add a new search engine in user configuration

Hi,

I would like to add the Qwant search engine (https://www.qwant.com/) in 
my search engines list and be able to use it as my default search engine.

I found those links :

http://blog.nixpanic.net/2014/07/change-default-search-engine-in.html
http://www.lifehacker.com.au/2015/02/how-to-change-the-raspberry-pis-epiphany-browser-to-use-google/

in which it is said to modify the gschema xml files in /usr/share and 
recompile them. I am reluctant to modify the main configuration files. 
Is there another way to do this? (gconf-editor, or user configuration 
files in ~/.config/ or in ~/.locale/share)


Regards

cedlemo.