Try what sixdogs says. I get mine at a logging supply store. There are a couple near by. Labonville also has some cheaper ones.
Choker Hooks
5/16" Choker Chain Hook
There is also BaileysOnLine you can google.
Shipping to CAN is probably high though. I run 5/16 choker chain and have a couple of the 5/16 ones and have not broken them.
Slip hooks are tough to use. You might have a little better luck if you use a double wrap like this - place the hook at 9:00 o'clock on the log with the hook point facing up and away from the direction you are going to pull. Wrap the chain up over the top, and around the other side. Come up just forward of the hook and keeping the chain tight cross over the first wrap just above the hook. Now make your second wrap behind the first and come up thru the hook when you come around. Now let the remaining chain hang down to the ground so you have a 180 degree turn of chain around the hook. That might help it stay while you walk away and start your pull. I rig chokers that way too on very light logs where the chain wants to just slip off because there isn't enough log weight to make the chain bite in.
gg