What would be the benefit of having 32 and 64bit in the same ISO?
i can see one benefit: Porteus is small enough to make it on 700MB CD with both (32/64) editions so you need to carry only one CD instead of two
that would be handy for PC repair service or such... (some old PC's may not have an option for booting from usb)
Anyway - (as pointed by Hamza already) automatic CPU arch detection would have to be performed by bootloader to find out which kernel should be loaded. this is not possible at the moment i'm afraid. maybe Grub2 will have this option in the future?
from_dir= cheat should work for ISO's as well so it should be possible to create Hybrid 32/64 Porteus ISO which contains both arch's.
i would like to see a syslinux menu containing 2 items: 'Porteus 32bit' and 'Porteus 64bit'. each menu would point to a submenu which would be a current porteus config with all booting options (text, copy2ram, etc)
i have a very little experience in creating syslinux submenus but maybe in my free time i'll prepare that ISO - just as another proof of concept
or maybe there is someone from the community interested in this challenge (just in case you would be bored enough over xmas period)?
Please add [Solved] to your thread title if the solution was found.