The pre-requisite abilities of your machine are two:
1. Disengage the feed dogs. If they work as normal they'll move the button so the needle and button will both break. If you simply set the dogs to not feed (zero), they will still push the button up and will break the button. They must be disengaged and lowered. All of my machines have a height adjustment for the feed dogs and once lowered below the throat plate, your button will be safe.
2. Zig-zag stitching. Your machine must obviously be able to stitch from one side of the button to the other. If the button has four holes, a diagonal stitch is best, if your zig-zag will reach.
Here is the relevant page from the 319K manual:
|319K Manual page 70|
Slowly hand crank while adjusting the zig-zag width until you're certain the needle will go into both holes before engaging the motor. Note the instructions for adding a shank.
I'm confident, after 10 buttons or so. It saves me a load of time and produces a consistent result.