As noted above, it is important to be aware that a reader-pays business model is not incompatible with open access. Many toll access journals empower their authors to make their works available through Green Open Access, and may even facilitate the process by providing their institution with the appropriate manuscript version to be archived in the institutional repository. Usually, they do so by creating clear Green Open Access policies, and including terms for Green Open Access in their standard author agreements.
Terms and policies usually specify what version authors can make available. Usually, it will be the submitted version, which has not yet been through peer review, or the accepted version, which is post-peer-review but does not include final formatting or copyediting. Terms usually also include the time frame in which the work can be made available, including whether or not there is an embargo, and how long the embargo is. Policies vary by journal and by publisher, and can range from allowing authors to self-archive the accepted version of their paper immediately, to allowing authors to self-archive the submitted version only after a year or more.