are you trying to say the guy partitioned his xbox hdd and has an os installed on the hdd and has a menu for boot options "xbox or os ect?" or did he build a pc inside an xbox case? sorry not trying to upset you any more than you already are i just need to be clear on what you are trying to do so i can help
build is my bread and butter so i should be of some help
are you talking about this "OS Xbox Pro" its called efiX try expresshd. blah hope this is what you mean if so 2 easy bro
and i dont know if you actually need this there are other ways to manage the boot menu besides this