This is my understanding from observation only. Please let me know if I'm wrong.
Poly's build and KaiserDroid both use an installer from boot to setup the filesystem, extract files where they need to be, etc.
Because of this installer that starts from the kernel (I believe), you can easily install/write over different builds all day long whether on NAND or HaRET/MicroSD.
That Donut build 1.6 in the thread you linked does not use the installer and may not have the needed software to boot from NAND for the Kaiser.
The software needed to run from NAND is not the same as what you need from HaRET.
If the kernel was the same I would say you probably just need to create the files where they need to be or use the installer from Poly/KaiserDroid with a custom androidinstall.tar. Since they aren't I expect this will be much more difficult.
IM(humble)O Your best bet is to either:
-- Learn about the flashing process, how NBH's work, etc. and what android requires to boot on Kaiser (or what the Kaiser requires to boot android
and then compile your own build of it (going to take programming knowledge on your part)
-- Ask the chef who made that ROM if they can make a copy of it that runs on NAND (hopefully they are still developing the ROM and interested and have the time and energy to do so)
-- Use one of the other builds prepared for NAND already (ie: Poly, KaiserDroid, etc)
AT&T Tilt (Kaiser): CyanogenMod 6 Kaiser [RLS5.2] - RC2 based, Radio 1.71.09.01
Sprint HTC EVO 4G: CyanogenMod 7.1
ASUS Transformer Prime: Stock (rooted)
Sprint HTC EVO 4G LTE: Stock