Print extra documents after posting delivery note

Hi

I need to print quality orders after posting a new delivery note using 365 for operations. In AX2012 I would have done this by modifying the afterOperationBody method in the SalesFormLetter_PackingSlip class. In 365 for operations I want to do this using extensions but cannot use a pre or post event handler on the afterOperationBody method as it is protected and I cannot see any delegates that I could subscribe to which would help. Has anyone done this or know how to go about doing this?

Any help would be much appreciated.

Thanks,
Joe