I found a few solutions. amember is creating a plugin just for me -- WordPress has a plugin called "Post Levels," which gives people a post level (in addition to user level). And one can define a post as being private, readable by a certain level only.

http://dev.wp-plugins.org/wiki/PostLevels

Also, a very prominent CMS designer/programmer (offering a customized package of WordPress as a CMS), personally told me he is currently writing a subscription script to work with WP for himself, and may share it with me. Stay tuned...

If any of these don't work, I might have to commission specific work.