In the shower, you can back up to the water and gently tip your head back. If you're concerned the water may trickle over your forehead, hold a rolled up dry washcloth above your eyebrows with one hand and shampoo with the other. It's not easy to shampoo one handed, but it's safer.
Good luck Tiger!
Edit: My mom wasn't comfortable with that due to spinal issues, and just went to a hair salon.