The link to the Answers thread shows some using it in Update, but that doesn't work for me. Seems like most people are still finding it buggy.
Try this one. It's got a few options, at least you can narrow down which update types work. Seems to work only in OnGUI with the system I'm on right now.
FYI the original was only firing Once. The UpdateType dropdown gives you the option of firing in a Update, OnGUI, LateUpdate or only Once.