It’s not possible, the double opt-in should be a general policy of your site. I can understand your needs, but actually it’s not possible (and for security reasons, I cannot derogate this rule… at least not until the plugin works in this way).
Actually I was using the double opt-in as an example as I would do that for all the forms (have them all be double opt-in). What I want is to be able to have different forms that might have different fields for each to collect different information. If that makes sense. Anyway, I see now how I can do that.