Easy2Boot – Easy2Boot allows you to add ALL and ANY .iso, .img, .ima, .gz files , all Linux LiveCD ISOs and Windows Install ISOs (XP through to Server 2012) to your USB drive and boot from any of them. Automatic menu system. Just copy over your files and boot – no special utility required, no linux cheat codes, no special knowledge. Fully documented. You can change the wallpaper, menu, change the language, text colours, etc. to suit you. UEFI booting supported.
See Tutorial #24 for booting UBCD4WIN from an ISO file.