You can get a list from CAA website.
I think Tiger helis do one, i guess they're kinda not far from your doorstep.
Most of the instructors that I know did they're AFIC course with Geoff Day who freelances to several schools. I can give you his number if you want, just drop us an email and i'll send numbers to you.
You do know that you must a) pass the commercial exams to be an instructor, b) doubt your sanity to let people try and kill you, c) wise to do your commercial either instead or as well.