I also tried to create a legacy boot key on a wily system for a wily boot key and was unable to. I even downgraded syslinux* to those in vivid and it still did not work. Ultimately, I had to create a vivid boot key then upgrade the system with do-release-upgrade to wily.
I also tried to create a legacy boot key on a wily system for a wily boot key and was unable to. I even downgraded syslinux* to those in vivid and it still did not work. Ultimately, I had to create a vivid boot key then upgrade the system with do-release-upgrade to wily.