Yes, it's possible. Look for this line inside qa_post_html_fields in qa-app-format.php:
$fields['tags']=' ID="'.qa_html($postid).'" ';
And change it to:
$fields['tags']=' ID="x'.qa_html($postid).'" ';
In the example above, we add an 'x', but you can change this to whatever you want.
Now you need to include this same letter every time Q2A builds a link which includes a post ID after a #. For example this line in qa-page-question.php:
And this line in qa-app-format.php:
In both cases, add the character (e.g. x) after the # symbol.
Also look for usage of qa_path() and qa_path_html() where the 5th parameter is specified. This is also an anchor. In this case, again, add the character before the parameter, if it's a post ID of some kind.