If they're sent in the same format as the payment tokens for Ingenico Connect, we shouldn't need any change in the queue consumer. We just need to update the Adyen gateway code in DonationInterface to add the shopperReference to the queue messages as 'recurring_payment_token'.
Yep, it looks like there's no changes needed to the queue consumer side of things which is great! I tested with a new Adyen recurring donation and it was saved to CiviCRM as expected with entries in the associated civicrm.civicrm_contribution_recur and civicrm.civicrm_payment_token tables.
I'll close down this ticket.