There seems to be a section in Volume II that seem to be asking you to do something that is not possible with regards to IP Accounting, and I just wanted to check I wasn't going mad!
According to the DocCD, IP accounting will only account for packets in the outbound direction NOT destined for the router: "Only transit IP traffic is measured and only on an outbound basis; traffic generated by the router access server or terminating in this device is not included in the accounting statistics"
However, in Lab 15 Section 7.6 It asks you to enable IP accounting to track acces violations on an inbound access list, and in the answers it shows it working for traffic coming into the router!?! As the packet is dropped by an inbound access list, it never egresses out of the router, so won't get accounted. I have tested this and confirmed that it does not account this traffic and does indeed behave as the DocCD indicates.
I also spotted this in the DocCD: If the access-violations keyword is specified and any IP access list is being used on an interface, then only process switching can generate accurate statistics (IP fast switching or CEF cannot).
Presumably this means you would also need to disable fast switching on the interface?