It's funny you should ask.
I started putting together some parallax scrolling code during some quiet time at work yesterday.
You're right about the power of 2 limitation so you are better off (as Jambo said) using tiled sprites and resetting them when they go off the screen.
I've attached the code I created for parallax scrolling. It works as it is but it's not complete.
Good stuff:
1) It automatically calculates the number of sprites required to tile horizontally
2) Layer speeds are calculated automatically but can be changed. Either individually, all together or you can change the relative difference in speed of each layer
Needs adding:
1) It is not frame-rate independent but that is an easy thing to do.
2) You can only scroll left or right, you can't jump to a particular location in the world but again this is an easy addition.
You will obviously need to change the "main.agc" file to use your sprites and your display set-up and not include my engine but I've included it to demo how to set p and run the scrolling system.
