Is there a way to have chat only appear on certain pages in my simple machines installation?

Yes, there is a way to conditionally load freichat based on the page.

When you install freichat in SMF, it adds its code to the file Sources/Load.php .

So open that file, and in the function loadTemplate() .

You can do something like this :

   $pageList = array(PUT_YOUR_PAGES_HERE) 
   if(in_array(CURRENT_PAGE, $pageList)) {

    $context['html_headers'] .= '<script type="text/javascript" language="javascipt"src="'.$boardurl.'/freichat/client/main.php?id='.$ses.'&xhash='.$xhash.'"></script>
    <link rel="stylesheet" href="'.$boardurl.'/freichat/client/jquery/freichat_themes/freichatcss.php" type="text/css" />';

   }

You need to modify above according to your needs..

$pageList = array(PUT_YOUR_PAGES_HERE)

Would the "put pages here" be something like "http://website.com/index.php?action...."

and would it be right after loadTemplate() or within the ()?

Can you specifically tell us on which pages do you want freichat to load ?

This may help us to think of a easier/better solution.

On certain boards within simple machines. And is it possible to have different chats going on different pages?

And is it possible to have different chats going on different pages?

How can different chats run on different pages ?
Or did you mean the chatrooms ?

Yes, chatrooms.

It is possible to have different chats on different pages but it will require some javascript modification.

If you want the chat to be loaded only on certain boards and not in any other(profile,home, etc) pages, then it becomes easy.
Let us know your requirements.