Mounting 'shelves' on a 57518 Lego conveyor belt
The picture you have does show a 57518 thread link, which is what you wanted to use.  For that, you can use the 1/2 and 3/4 pins to attach a liftarm.  A 1x5 liftarm would match the width of the 57518 thread.  What's shown in the picture is a 1x7 liftarm which allows the module to lift more balls.
For the pins, you should use the 3/4 pins part 32002 to be perfectly legal, but some might also use the 1/2 pins part 4274 to add friction to the connection.