How do you customize the title of an RSS feed created by Views RSS?
Not sure how much this will help as its not exactly what you're asking (i think):

I was using views_rss to show comment threads to a question_answer module question. But I wanted the question to show up as the 1st time in the RSS feed (as RSS feeds) may only show 1 piece of data by their nature (eg, comments or new posts or blog posts) ...

I didn't muck with the title of the Feed because I saw issues with Firefox Sage vs. Google Reader as what the "title" of the RSS feed is -- so I stuffed the "FAQ question" to the comment thread at the top of the RSS feed ....

/**
 * Implementation of hook_views_pre_render().
 *
 * For the comment rss feed we want the description to contain something such
 * as "topic #N: topic text". These values are excluded in the view already.
 * The RSS feed supports a description field but cannot have PHP code in it,
 * it's just static text.
 *
 * This is a means to theme the RSS description field for valid RSS feeds. The
 * view enforces that the parent node is published, and that comments are
 * published as well.
 *
 * http://stackoverflow.com/questions/4011505/how-can-i-add-a-summary-row-to-a-drupal-view
 */
function MYMODULE_discussion_views_pre_render(&amp;$view) {

  if ($view-&gt;name == 'MYVIEW_discussion_comment_rss' &amp;&amp;
        $view-&gt;current_display == 'feed_1') {
    # Insert the question as a leading comment for this feed.
    $question = node_load(array('nid' =&gt; ARG(3)));
    $qrow = new stdClass();
    $qrow-&gt;comments_subject = htmlentities('Question Was:');
    $qrow-&gt;comments_comment = htmlentities($question-&gt;field_topic_text[0]['value']);
    array_unshift($view-&gt;result, $qrow);
  }
}


EDIT: My answer was coded for a D6 site, but the exact same principal applies to D7 (and I think the code as well).