I've used MS Detours to hook my own C++ interceptor functions into dispatch from Excel to XLL extensions via the internal Excel4V interface. It worked very well

I've used MS Detours to hook my own C++ interceptor functions into dispatch from Excel to XLL extensions via the internal Excel4V interface. It worked very well, showing me the XLOPER values. But that was for a 32 bit Excel. I didn't appreciate how much trickier it is with the amd64 instruction set.