The best way would be to go through IRTRAD. if you are subscribed. There are a couple of folk on there that could probably set you up quickly with an ABC, as it doesn't seem to be in any of the online collections currently.
By clicking on the User Name, you will requery the forum for that user. You will see everything that he or she has posted with that Mudcat name.
By clicking on the Thread Name, you will be sent to the Forum on that thread as if you selected it from the main Mudcat Forum page.
By clicking on the Subject, you will also go to the thread as if you selected it from the original Forum page, but also go directly to that particular message.
By clicking on the Date (Posted), you will dig out every message posted that day.
sj