My only offerings for /G and pos are this and this from the Pattern Finding thread (it does use pos() as an lvalue...).

And for /g, a thing to split up a block of text, preserving existing line breaks, but having a max line size:

print $1,"\n"
   while $text =~ /([^\n]{0,$max_line_size}})\n?/g;
[download]

Oh, and a '/g' example from a recent thread (of which you've probably already got something similar).

And this thing which reads from a socket until I have an end-token on a line:

while ($sel->can_read) {
  sysread($fh, $buffer, 2048, length($buffer));
  next unless $buffer =~ /^(EOT|DONE)$/m;
  ....(process $buffer)
}
[download]