This appears so obvious that I must be missing something, but...
I am trying to include the RTCESL in my bare metal project. The User Guides for MLIB and GFLIB both tell me it's easy (hmm, heard that before...) - just pick the development board and then select it from the middleware tab. The processor I am using (MKV10) isn't supported directly, and anyway I have a bare metal project. If you are not using a development board, you don't get that option in the middleware - it just doesn't appear on the list. I am scratching my head as to why not, because it is not hardware-specific.
If I place the libraries in C:\NXP\RTCESL and then add includes in project->settings->includes I can see all the files in the project explorer, and it finds the .h files, but the build fails because it can't find mlib.a (even though it is being displayed in the explorer and I added another include because it is one layer up in the file hierarchy).