transform title/@xml:id to title/@id in HTML

Hi everyone,

I'm using the DocBook XSL to transform DocBook XML to EPUB and HTML. I have a question about including xml:id in the output as id's. 

I know that it's possible to include the xml:id of main sections in the output using generate.id.attributes. I also have xml:id's in some of my <title>-elements, and I would like to add these in my output too, like this:

Input:
<preface><title xml:id="12345">...</title></preface>

Output:
<section class="preface" title="Frontispice" epub:type="preface" id="56789">
  <div class="titlepage">
    <div>
      <div>
        <h1 class="title" id="12345">Frontispice</h1>
      </div>
    </div>
  </div>
</section>

Is there a way to do this? 

Thanks in advance,
Kind regards,
Michel