I have one Rottie that LOVES the treadmill and one that is sure it will eat her...
I also have a Chow Chow that will willingly trot on it for a while...
The most important thing is NO FORCE!!! Let her get used to the sight and sound by you walking on it. Pretend you are having SOOooo much fun. Then when you think she's ready, use a really nummy treat and coax her up. (With TM OFF of course!) Reward for even one paw. If she's scared, just ignore her and pretend to have even more fun on the now turned off TM. Try again later and keep thinking "baby steps".
When she is comfortable standing where she should and is not frightened whatsoever, you can stand, straddling her to keep her steady and more importantly, safe. Get her used to that and when you think she's ready, you can start the machine. VERY slow. You must be ever so carefull with this stage. If she gets frightened or gets her toe stepped on, she may never be comfortable with it again. Use your most confidence building praise voice to let her know she is the BEST doggie in the whole world and end it there for the day! It will be so tempting for you to rush the process but believe me, it will be worth it if you don't and may be disastrous if you do!
Good luck and be patient! :D