Creating additional iPhoto libraries isn't a difficult process. While it's true that iPhoto can only work with a single library at a time, it does support multiple libraries. You can choose the library you want to use when you launch iPhoto.
The process of creating an iPhoto library is fairly simple; we outlined a step-by-step process in the iPhoto Libraries - How to Create Multiple Photo Libraries in iPhoto '11 guide. Follow this guide to create the iPhoto libraries you plan to use.
The new iPhoto libraries will be empty. You'll need to export images from your original iPhoto library, and then import them into the libraries you just created. You'll find some helpful guidelines, as well as a step-by-step outline of the export/import process, on the next page.