It would be very hart to put related news in middle of article body, however if you mean to place it on the right side of article body (like in version 3.4) you can do next:
Open your article_Full.tpl template and around {ARTICLE_RELATED_NEWS} tag wrap div with these styles <div style="float:right; width: 200px;">.
Next, place this div right above article image code, so the entire block of code would look something like this:
<div id="article_body">
<div style="float:right; width: 200px;">{ARTICLE_RELATED_NEWS}</div>
<img src="{ROOT}files.php?file={ARTICLE_IMAGE}" alt="image" align="left" border="0" />
{ARTICLE_BODY}
</div>
This would give you related news box 200px wide and aligned on the right side of article body with text wrapping aroind the box.