Send message to listing agent thought buddypress

Hi,

I wounder where I can put the following code to implement
a message button to send a private message trough
buddypress, rather than a listing agents contact form.
(a message copy to their email is sent anyway by BP)

… an if the code gets the listing agent?

/**
* Add buddypress message form after agent info
*/

function bp_custom_get_send_private_message_link($to_id,$subject=false,$message=false) {

//if user is not logged, do not prepare the link
if ( !is_user_logged_in() )
return false;

$compose_url=bp_loggedin_user_domain() . bp_get_messages_slug() . '/compose/?';
if($to_id)
$compose_url.=('r=' . bp_core_get_username( $to_id ));
if($subject) 
$compose_url.=('&subject='.$subject);

/*if($message)
* $compose_url.=("&content=".$message);
*/

return wp_nonce_url( $compose_url ) ;
}

//for auto populating message content 

add_filter('bp_get_messages_content_value','bp_custom_message_content_value');
function bp_custom_message_content_value($content){

if(!empty ($content))
return $content;
$content=$_REQUEST['content'];

return $content;
}