Well, since I can't comment on that convoluted site, a quick gotcha with 'pbpaste' and 'pbcopy': they don't work with screen.
EDIT: This issue no longer exists. Kindly ignore my comment.
EDIT: This issue no longer exists. Kindly ignore my comment.
bindkey -m > eval "stuff ' '" writebuf "exec sh -c 'pbcopy < /tmp/screen-exchange'"
then when you've made a selection in screen Copy Mode, just terminate it with '>' to stick it onto the system paste buffer.