Return the value of a function with Forms Personalization

I'm trying to personalize the Sales Order Lines form with Forms Personalization. I want to create a button under the special menu, so that when it's clicked, it will return the value of a pl/sql function.

So, in forms personalization, how/what can you create to return the value of a pl/sql function from the special menu.

There is an option to 'execute a procedure', but this won't accept a return value.

Can anyone help?

Thanks,

Gary