My only qualm is where is this kernel coming from and why is there no other way to run this then with a specially built kernel. Im sorry to say, but I can't just trust anything that replaces my kernel, no matter who it comes from when that person isn't my OS vendor.

Is it impossible to get teh same thing done with a kernel extension?

I would very much like to see OSX ship with truss; in particular, I would like it to be the Solaris-style truss that can trace descendents of processes, etc. (The FreeBSD version is only a pale shadow of this.) Anyone who agrees with this wish might want to send a note to devbugs@apple.com, supporting Problem ID #3121601.