RXML vs form_tag etc

Railsers:

The documentation for *.rhtml views invariably mentions *.rxml views.

They sound like a Good Thing, because some of my generating code mixes
Ruby and HTML so densely that the code is full of %><% markers.
Dropping down to only one language would be a blessing.

However, this documentation invariably avoids mentioning one tiny,
insignificant detail:

How do you inject raw HTML into a Builder::XmlMarkup builder?

Each time I try, the Builder escapes everything, as if my users wanted
to see my <form> tags and such, raw in their browser.

So if I wanted to put form_tag and other view helpers into a Builder,
how do I unescape the HTML they create?

How do you inject raw HTML into a Builder::XmlMarkup builder?

  # * The special XML characters <, >, and & are converted to &lt;,
  # &gt; and &amp; automatically. Use the <tt> << </tt> operation to
  # insert text without modification.

Bleah!