[fdkz]

Replying to myself. Using mkfifo is not necessary:

    import os, sys, time, subprocess, fcntl
    sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)
    read_fd, write_fd = os.pipe()
    fcntl.fcntl(read_fd, fcntl.F_SETFL, os.O_NONBLOCK) # don't know of any windows equivalent for this line
    proc = subprocess.Popen("ping www.google.com", cwd=sys.path[0], stdout=write_fd, stderr=write_fd, shell=True)
    while 1:
        try:
            s = os.read(read_fd, 1024)
            if s:
                sys.stdout.write(s)
        except OSError:
            pass
        time.sleep(0.1)