You probably mean the upload_hook() method. The following is right from the CGI.pm docs:

You can set up a callback that will be called whenever a file upload is being read during the form processing. This is much like the UPLOAD_HOOK facility available in Apache::Request, with the exception that the first argument to the callback is an Apache::Upload object, here it's the remote filename.

$q = CGI->new();
$q->upload_hook(\&hook,$data);

sub hook
{
       my ($filename, $buffer, $bytes_read, $data) = @_;
       print  "Read $bytes_read bytes of $filename\n";
}
[download]

Make sure you have the latest version of CGI.pm installed, as I think this was just added in the 3.x version.

- Cees