I've found the trick to add it.

I've download Chrome Extensions Addons for Opera : https://addons.opera.com/en/extensions/details/download-chrome-extension-9/?display=en

Then i've found the Lilo Chrome Extension : https://chrome.google.com/webstore/detail/lilo/jkoegdibpkleifbkojmplebjhfllkckn

And it's working.

Hello,
I'm a french guy and i want to use "Lilo" which is a websearch engine, for the moment it doesn't support Opera browser.
Can you help me to add it on Opera ?
http://search.lilo.org/

Thanks