Yeah, I was aware of that. Naughty Dog did a similar thing with their toolchain.
Lisp seems to have been damaged by the functional programming dogma more than anything else, the more I learn about it. Which is a shame, because the functional parts are good. But so were all of the toolchains around interop with other systems.
In Steel Bank Common Lisp, one can just write a new VOP to emit a new instruction.