Tracking IPC calls

All, We are working with the Fiasco kernel on x86 arch. We are trying to track IPC messages between processes and maintain a buffer of them in a data structure inside the kernel, maybe buffer to a deticated user space server later. Any pointers as to the best place to add our hooks? We've been playing around with l4/kernel/fiasco/src/kern/shared/idt.cpp. Not sure if we are on the right track or not? Any suggestions? Thanks! -Julian