Could you specify what do you mean under image from the internal storage?It's the same, because we just write a identical image from the internal storage to the SD-Card.
I try to boot uImage I've compiled and moved to SD card by usual file copying like described here: http://nookdevs.com/Building_the_Nook_Touch_stock_kernel
In this case SD card partitioning may vary, so I'd like to ensure I haven't a significant differences with successful cases.
Do you mean that creating one FAT32 partition from 16384 to 79691775 block at SD card and marking it with boot && lba flags is the best case to check it?