Add Subscriber Function

I’m using the cforms plugin to create ‘contest entry’ forms…

cforms allows me to add a ‘check box’ and call a php function if that check box is checked upon submission.

I will be adding a ‘subscribe to newsletter’ check box on my contest entry forms… is there a newsletter php function i can call and pass the users email address to trigger the double opt-in process?

Thanks,

http://wordpress.org/plugins/newsletter/