1. you need to set the livebox with your username and password this is usually done by connecting by cable first and then configuring the wireless.
However orange say you can connect to the wireless first.
2. I use a wireless adaptor in an old laptop to connect to a livebox OK.
You can by a PCMCA card with ethernet connection to fit the laptop if you have card slots.
But this is expensive just to set username and password in the router.
Do you have a desktop?
Can you get a mate with a laptop with ethernet port to come round while you set up the livebox?