Okay, I was being a bit cruel. It can be done with the latest client, but it needs a particular string to be present in the 46xxsetting.txt file to allow the user to switch it on/off and sadly that's not in the current auto-generated settings file and you can't use the specials file with Workplace on IP Office - all things that were on the R11.2 list up until Avaya did its recent planning reset for all products.
If I understand correctly, its supported by the 3.30 Windows client and needs the string AUTO_ANSWER in the settings file. So its a client thing only, not related to any auto-answer settings in the IP Office (for example, I would assume that when a user has it switched on, that doesn't mean the IP Office will treat the client as something it can page).
Stuck in a never ending cycle of file copying.