Chat tools can be difficult to use for online teaching – typically, with 20 or more students participating, all seeming to ask questions at the same time or having separate discussions, the chat can get very busy and hard to follow.
However, used with some sort of protocols in place, they can be managed effectively to provide an effective online tutorial. I have been involved with a number of very successful online chats, where senior editors from major international publishing houses have discussed writing and publishing with writers. These chats were set up with a few simple protocols for those participating, and flowed well, with the guest experts not overwhelmed with questions, time to respond, and much learning for all involved.
In the current issue of Innovate, the journal of online education, Craig W. Smith's article Synchronous Discussion in Online Courses: A Pedagogical Strategy for Taming the Chat Beast provides a good outline of a suggested 'Virtual Class Chatiquette' to enable effective use of chat tools in teaching.
The approach described by Smith is similar to the simple one I've experienced, and can be used both for tutorials with the course coordinator, and for chats with guest experts, whether the expert is in your office or half a world away at their desk – another one of the benefits that online teaching brings.