Use Tipsy code in a field rewrite?

[This will require some background explanation.] A View is displaying a custom content type. With Flag Lists added it provides the option to select items via checkboxes and add them to a personal list. However some items are excluded from being available to add to such lists, which was established by a boolean checkbox ("allowed" if checked) in the creation of the node. If NOT checked, the Flag List Operations checkbox in the View is rewritten by something else – currently, replaced by a simple text "X".

Now we want to provide a tooltip message explaining why this item is not available to be selected, using Tipsy. It seems we can't use a CSS class because it would either apply to everything, or to just one instance and would have to be specified separately for each instance, using a unique selector each time.

It looks like a Views field rewrite might get us there but we are not seeing exactly how. If the following code –
<div class="tipsy-inner">Internal Access Only</div>
is put into the same rewrite field as the "X" mentioned above, a Tipsy message appears in the expected style. However it is constantly there. How might that code be extended to make it act like normal Tipsy tooltips, i.e. it appears only upon hover?

--Thanks--