I could be wrong, but it looks like you can edit the list of fields to display by changing $self->{Field_Order}. For instance, if you're calling success_page_fields() as follows:

success_page_fields($hashp);
[download]

You can edit the list of fields with the following:

$hashp->{'Field_Order'} = ['field1', 'field2', 'etc'];
success_page_fields($hashp);
[download]