How do I use AJAX to reload partial page content without using an external file?

[zoldos]

I run a social networking site and it has an advanced newsfeed feature. I want to use a clickable AJAX link to refresh just the newsfeed and not the entire page. The code is held in a javascript tab as seen below and I've already added a basic link to refresh the entire page but this is slow and cumbersome. The specific code that produces the newsfeed is here:

{he_wall_display object='userhome' object_id=$user->user_info.user_id}

This *cannot* be held in an external file...

Here is the code with the tab:

<div id='profile_activity'{if $v != 'activity'} style='display: none;'{/if}><br>
-=<a href="javascript:location.reload(true);" target="_self">Click here</a> and then click the activity tab again to refresh site updates=-<br>
{he_wall_display object='userhome' object_id=$user->user_info.user_id}
</div>

Any suggestions would be greatly appreciated! Thanks!