Hi,
It is possible to display the "add to wishlist" button when the user is not logged.
But for the moment it just display a message telling that the user need to log-in.
In the file "components/com_hikashop/controllers/product.php" you can see to modify the code after
else if($cart_type == 'wishlist'){
if(hikashop_loadUser() == null){
In order to redirect the user to the login page with as parameter a link to the previous page (so when the user will log-in, he will be redirected to the page he was before).
It is also possible to place a link to add the product to the wishlist ; using an "update cart" link.. But it will require some development.
Regards,