Put slide.sh in your path or just invoke it via bash:
$ bash slide.sh my_slides
See the upstream repo for all the cool things you can do with formatting and stuff.
In this fork you will no longer be sending slide content as input to a
slide command; rather, you just put the content in a file and separate
each slide with the text slide on a line by itself.
I've also added !!vcenter which starts your content halfway down the
screen.