UEFI booting is a mine field as every element in the process has to be 64-bit. This is not an Altiris constraint, but one that is implicit in the technology itself. When you add secure boot to this, you also add another constraint that your DVD drive's storage controller firmware needs to be both signed and authenticated.
In short, you are going to have a lot of trouble with UEFI and secure boot I think in general until this technology area matures. Microsoft's angle with secure boot is that it is intended to help secure the machine after the OS is installed. This is why a lot of advice from Microsoft on this topic is to disable secure boot prior to the OS install, and then enable it again afterwards.
Kind Regards,
Ian./