I tested 5 different official and unofficial ALT Linux isos writing them to a USB and after isolinux menu there is a message that the cd rom could not be loacted so u want to retry, if choose no it will look for usb source and fails to find it as well even that the image has been booted from a usb.
The images are hybrid ISO indeed but looks like something's wrong with propagator (which has been patched to cope with an ISO booting off a USB flash).
Please try one of these if the hardware at hand is x86_64: http://ftp.linux.kiev.ua/pub/Linux/ALT/people/mike/iso/mkimage-profiles/efi/ -- the images have somewhat different isohybrid processing. I can also reprocess any existing image you'd be interested in.
There are newer installable LiveCDs including KDE4: http://ftp.linux.kiev.ua/pub/Linux/ALT/people/mike/iso/mkimage-profiles/half-/ x86_64 images are UEFI bootable, and tomorrow's crop should also be able to deal with SecureBoot to some extent either. These are also hybrid (dd to a flash).