RCCE is still designed to work on baremetal, but work on its baremetal version is not as up-to-date as work on its SCC Linux version. So in the near future you may come across issues when working on baremetal.
MS_BAREMETAL refers to Microsoft's baremetal Visual Studio plugin. This plugin is not currently publicly available.
By modifying page tables, you are essentially modifying the OS. I don't think this is something you would want to do (even if you could) from the application level. The source code for SCC Linux is available, so you can investigate that area if you want.