[jQuery] How to edit a portion of text

Hi,
I have a portion of code like:

<div class="hentry">
    <p><img width="160" height="120" alt="00000" src="/
img_2009/51/00000.jpg"/>
    Text fo the article excerpt
    <br/>
    <span id="more-00000"/>
    text of the article after the excerpt, and so on, and so on, and
so on, and so on,
    <a target="_blank" href="">link</a> and so on, and so on, and so
on, and so on,
    and so on, and so on, and so on.
    </p>
</div>

I need to edit it like:

<div class="hentry">
    <p>
    <strong class="excerpt">
    <img width="160" height="120" alt="00000" src="/
img_2009/51/00000.jpg"/>
    Text fo the article excerpt
    </strong>
    <span id="more-00000"/>
    text of the article after the excerpt, and so on, and so on, and
so on, and so on,
    <a target="_blank" href="">link</a> and so on, and so on, and so
on, and so on,
    and so on, and so on, and so on.
    </p>
</div>

How can I achieve that?

Thanks