Running power wire for HU

I just got my Clario DXZ 835MP and I am running wires.  The instruction manul calls for the power wires to be run to the battery.  I found the groumet containing all my wires underneath the stearing column(2003 Carmy BTW), and I took it out.  I made a slit insiscion and manage to get the wire through.  My question is, the wire is 12 guage and how can I attach it to the battery?  I accidentally bought a terminal from autozone that is for 4 guage crimping and I realized that right as I got home, oops.  Unless I could try and solder and squezze the 12 guage in there how else could I do it.  Also was the way I ran the wire ok?  (Through the gromet already there)  Thanks for any help.