# Select the form
my $perl_form = $ie->form_name('form1');

# Get a pointer to IE's DOM object.
my $form = ${$perl_form};

##</code><code>##

my $doc   = $ie->Document;
my $form  = ${$ie->form_name('...')};
my $field = $doc->createElement('<INPUT TYPE="hidden">');
$field->name  = '...';
$field->value = '...';
$form->appendChild($field);