Abunadh,

I am not aware of any speaker terminals that do not require some form of soldering for 8ga wire, it's very thick. I think you have two options, find a friend who has a soldering iron & solder or get a cold solder kit.
Just make sure you get a good solder connection between the internal speaker wire and speaker terminal tab.

Parts Connexion has a good selection of speaker terminals which accept larger gauge bare wire or spades. You can email or call them for suggestions based on you speakers and equipment.

Good luck.

HK