won't be the same for yours but for those with a bumper pull:

I bought a snap that I could hook through the loop on the break away cable and then I just clip it onto the hitch pin.

I am no expert but think of it this way.  Attach your emergency break away cable to anything but a part of the hitch.  Think of it this way,  your hitch fails catastrophically and breaks away from your truck,  your trailer,  your hitch and your break away cable go flying down the highway.  Now think about this,  you attach your breakaway cable to the bed of the truck,  maybe even the holes in the bed rails where you attach tie down straps.  You have the same catastrophic failure,  your hitch breaks agway from your truck,  the hitch and the trailer seperate from the truck but then the break away cable which is attached to your bed rail pulls the pin on your breaks and your trailer hopefully will come to a stop.  Am I right in this thinking?

I hook mine to the safety chain but I am not sure that is the legal way to connect. I think it needs an independant connection.

In my Chevy truck, I have metal "loops" welded inside the bed, near the tailgate.  I use a heavy duty trigger snap to attach the breakaway cable to this loop.  My thought is I want the break away brake to activate LAST in the event of an unexpected disconnect.  This is the sequence I want things to happen, if they ever do.  First, the goosneck hitch becomes disconnected from the ball (or the ball comes disconnected from the truck).  I still have SOME control of the trailer because my safety chains are intact, the gooseneck is still contained within my truck box, and I have connection to the brakes on the trailer through the electrical hookup.  Second, the safety chains fail.  I still have very limited control of the trailer because I still have brakes through the electrical hookup and the neck of the gooseneck is still located inside my truck box.  Third, the gooseneck exits from the bed of the truck and I lose my electrical connection.  THEN I want my breakaway brakes to activate.

My opinion is if your breakaway brakes activate after the gooseneck disconnects, but before your safety chains fail, you are for sure going to lose the chains and your tailgate and your trailer is under no directional control at all.  I only want my breakaway breaks to activate if I have lost the gooseneck hookup, the safety chains, my electrical hookup and my tailgate.  I therefore make my breakaway cable the very last to activate.