with xconfig. look under " processor type and features "
it's " preemptible kernel " your looking for i guess.
also i think you need the " realtime " module, that can give users realtime capabilities. ( maybe you already have it, but anyway...)
read the readme etc.
it requires also to select under " security " the option "capability " to be a module.
more info in the readme + doc.
btw...if you use it, either the realtime or the capability module can be loaded.
(for ex.: i can run bind or make music, not both cuz bind/named needs the cap. module )