I've recieved one day mutes for using Shortkeys; I'm assuming autotyping is worser so the penalty may be longer but I doubt they'll issue you with a ban.
Put the speed on it fairly slow (a few seconds apart), so that nobody can tell whether you are auto-typing, or whether you are just simply typing out your message yourself
I think the worst that can happen if you are reported/caught though is just a temporary mute. I know quite a few people who it has happened to while they were advertising for people gilded altars on w31, or for dicing clans. This was all pre-bot nuke though so I'm not sure whether they are cracking down on all types of macro's now, in which case it might warrant a more severe penalty.