We added beads to a nightgown in Pfaff class years ago. Found the instructions - this was for a Pfaff 1473/75 machine so you would have to play.
Straight stitch in center needle position - presser foot removed.
Feed dogs dropped
Presser foot in darning position
Take a few stitches to lock thread
Position the pearl on the needle and lower the needle into fabric to take one stitch.
Take another stitch right beside the pearl, then a few stitches to tie off threads.
This was based on a project from Sharman Dorsey back around 1992 -4
It was with a pattern. I very much doubt that any of this is around anymore. There are still Pfaff 1400 series but not much written. I kinda miss them - you designed stitched by coordinates called B00 L00