to boot module from kernel stored in fat32 partition on sd-card you should do from u-boot:
dboot linux mmc 0 fat
dboot linux mmc 1 fat
one for SD one for uSD
The second partition should be EXT3 and contain your rootfs files (extracted, not image)
this document talks about how to boot android from sd card, but android is based on Linux so you can figure it out:
booting android from SD card
if you have installed DEL you'd have images in /usr/local/DigiEL-5.9/images/ccwmx53js/ folder
The easiest way to boot your board without touching FLASH is to boot from tftp/NFS ("dboot linux tftp" command from u-boot)
you can also partition your FLASH to have both Linux and CE images at the same time and boot either one with a key press is you set u-boot environment variables:
key1=dboot linux flash
key2=dboot wce flash