Wedges are cut on a band saw jig which is simply a piece of plywood
with a notch cut out which runs against the rip fence.
The slots I cut on the band saw too, making each slot the width
of two band saw blade kerfs, so about 3/32”.
I use glue too, just as normal with a mortise and tenon joint,
brushing it on the cheeks and sides of the tenons. I didn’t
use glue on the wedges. Once cut off flush the chance
that they would somehow wiggle loose is remote, imo.