To make it easier, why not just add opera to your sources.list file?
So, become root, type nano /etc/apt/sources.list
and add one of these two lines:
For AntiX 6.5 (Ubuntu base):
deb http://archive.canonical.com/ubuntu dapper-commercial main
For AntiX 7 (Debian base):
deb http://deb.opera.com/opera/ stable non-free
That way, you can just apt-get install opera & be able to get updates for it.