If you want to use the Jack low latency audio server (Jack Audio Connection Kit) with realtime privileges (SCHED_FIFO) then the obvious alternative is to build and load the LSM kernel module[2]. Regretfully that would need CONFIG_SECURITY_CAPABILITIES to be a module instead of being built into the kernel, as in the last build I tried (otherwise you can't build the LSM module).
If i run JACK as root, do i still need the LSM module?
No, sorry, you don't need it. I should have been more specific. That's only necessary for getting realtime privileges as a non-root user.
-- Fernando