Previously I showed several different methods of machine made buttonholes HERE. These were all done on Singer machines with various attachments or using the 3-needle positions to make them freehand.
Buttonholes made on Kenmore 158 with "lollipop" guide
The vintage Kenmore 158s I've used don't have three-needle positions and they don't have a built-in buttonhole stitch, either. Early Kenmores did use a buttonholer attachment like the Greist model that Singer used, but the later 158s had an entirely different system.
It's pretty simple to use, and makes acceptable buttonholes. That's about it!