Someone (older) recently asked me for the link to “how people are selected”. Here it is. Unfortunately it is the legal-ese, and doesn’t tell you how to go about actually getting on a study section (if you are not ECR material).
My best advice – find an SRO and send them an email. Remember, its seldom a good idea to cold call anyone at NIH. An email asking for a time to talk about a particular subject has, for me, always worked best.