There is plenty of documentation on ways to distribute iBooks to iOS devices, but I require a way to distribute iBooks to users' macbooks and self service would definitely be a preferable way to do this.
I am currently using composer to package the iBook and then adding a postinstall script to open the iBooks file so it is added in to the user's ibooks library and then delete that ibook from the install location. This does work, however an easier way to do this would be preferable.