Look at an example here:
http://www.zend.com/codex.php?id=165&single=1
This is a little code I wrote to update DHS.org hosts, which uses fsockopen and the POST method to get results. Notice after you open the sock, you can do while(!feof($pointer))
$buffer.= fgets($fp, 1024);
which will return the results from the POST into $buffer (or whatever). Hope that helps.
Chris King