14 Day Free Trial before card is processed using Magento and Subscriptions

[germinate11]

We have a client that is using the following framework: 

Payment Gateway: Authorize.net with CIM and ARB

Shopping Cart: Magento

Subscription Extension: Subscriptions and Recurring Payments by aheadWorks

link: http://ecommerce.aheadworks.com/extensions/featured/subscriptions-and-recurring-payments.html

They want to be able to give new subscribers to their service a 14 day free trial, which the subscriptions plugin does not support out of the box. I spoke with Auth.net support and they said this can be done using the ARB service. Our client is signed up for both the ARB and CIM services. 

However, after endless searching and trial and error I am unable to figure out how to get Magento to talk to ARB and set up a recurring payment that will be charged 14 days from the date they subscribe (and then not after that because the subscription plugin handles the rest). Has anyone done this before or found a work-around for such a setup? 

Thank you!!

[TJPride]

It's written in PHP, so I would think that anyone who knows Magento wouldn't have -that- hard a time interfacing with Authorize.net. Going the other way around, on the other hand, is going to be next to impossible. I would recommend hiring someone who knows Magento well, they'll know where the code needs to be put in, and whether it'll be easier to do ARB + callback or CIM with automated billing every morning.