checking the MAS receipt for an in-app-purchase

I’d like to be able to check the MAS receipt for an in-app-puchase item. I’m already using Thomas Tempelmann’s Cert-Tools to validate the receipt, but I don’t know how I can access the in-App-Puchase data, which afaics and according to Apple’s docs should be possible. Any pointers?

I added plugin classes for that. Will email you a copy to test.

Will appreciate a copy to test too. Thank you!