Yes AA should be possible, from those points,
Guideline 1. Provide equivalent alternatives to
auditory and visual content.
Guideline 2.Don't rely on color alone.
1. ie. for images add alt text etc.
2. make sure the design of your skin does not rely on color
These parts are not dependant on which version of DotNetNuke you are using, they are dependant on your skin design and how you add content to a page, ie. when adding text and images into a Text / HTML module.
Another element worth considering is:
Semantic Code and Header Tags in DotNetNuke Skins