If your host is using suPHP, you can try creating a php.ini file in the same folder as the script and adding:
allow_url_fopen = On
(you can determine this by creating a file and checking which user it was created under: if you, it's suPHP, if "apache/nobody" or not you, then it's a normal PHP mode. You can also make a script
To give the same information, assuming shell_exec is not a disabled function)
