Workflow transition form ignores elements added w/ hook_form_alter?

Hi,

My goal is this: 1 workflow field shared on 2 content types, at certain states, additional information added to the transition form & put into node fields. Also at some point it needs to switch from one node to the other. I imagine this is doable in code, but the first hangup is one i didn't expect. I am rendering the transition form in a custom block like this:

function mymodule_block_contents()
{
  ...
    if ($current = workflow_node_current_state($n))
    {
            $bundle = $node->type;
            $field_name = 'field_my_workflow';

            $workflow = workflow_get_workflows_by_type($bundle, 'node');
            $field = _workflow_info_field($field_name, $workflow);
            $entity_type = 'node';
            $instance = field_info_instance($entity_type, $field_name, $bundle);

            $form = array();
            $form_state = array();

            $f = drupal_get_form('workflow_transition_form', $field, $instance, $entity_type, $n);
            //hide the comment box
            $f['workflow']['workflow_comment']['#access'] = FALSE;
            //hide the button for the current state
            $f['workflow']['submit_sid'][$current]['#access'] = FALSE;
            $f = drupal_render($f);
            return $f;
     }
}

and want to add elements above or use form alter to add the elements and additional submit handler.

...

function mymodule_form_alter($form, $form_state, $form_id)
{
  if($form_id == 'workflow_transition_form')
  {
    $form['myelement'] = ...
  }
}

But the custom element never shows up in the form, whether i put myelement as $form['myelement'], $form['workflow']['myelement'], or $form['workflow']['workflow_sid'][$sid]['myelement'], and it doesn't matter whether i do it in form_alter or in the original block_contents. Also no effect when i add a function to the #submit arrays. It never gets called.

Any ideas? I would like to access the submitted values in either hook_workflow or a custom submit handler.

Thanks much.