How to implement 'set -o pipefail' in a POSIX way - almost done, expert help needed

Question

I have to implement the BASH set -o pipefail option in a POSIX way so that it works on various LINUX/UNIX flavors. To explain a bit, this option enables the user to

Answer 1

My two cents:

#!/bin/sh

# Saving the pid of the main shell is required,
# as each element of the pipe is a subshell.
self=$$

lots_and_fail() {
    seq 100
    return 1
}

{ lots_and_fail || kill $self; } | sed s/7/3/

This thing seems to do the job. Thoughts?