This is not achievable.<p>There isn't enough rewritable microcode to do this even as a super slow hack.<p>And even if all of the microcode were rewritable, ucode is kind of a fallback pathway on modern x86 cores with the fast path being hardwired decode for x86 instructions.<p>And even if that weren't the case the microcode decode and jump is itself hardwired for x86 instruction formats.<p>And even if that weren't the case the microops are very non-RISC being 2 address, etc.
This type of contest style recruiting just seems like a way to trick people into writing code for free, and even if you do win the prize money seems laughably small for what they're asking to receive.
I think a more realistic thing would be adding a few custom OPs to make binary rewriting more performant.<p>Another interesting thing would be implementing a subset of RVV with AVX512 hardware primitives, although idk if/how they are exposed in micro code, amd you likely would need to use a different instruction encoding.