Yep, I read that site a lot... A lot of the discussion is over my head, though, so I have not posted there...
I think there may be a bit of confusion, which for a Monday morning on only one cup of regular coffee is outstanding.
There are actually four options being discussed here:
1. Leave the Nook Color alone. Do nothing but happily read B&N books magazines and use the three overpriced apps from their little boutique app market.
2. Completely remove the B&N version of Android and replace it with a custom rom like CM7 or Phiremod turning it into a fully functional Android Tablet.
3. Root the Nook Color but leave the B&N Version of Android in place giving you the option to use it as a stock Nook but having access to the market and apps.
4. Leave the B&N Android system untouched and boot a full version of Android from the SD card.
Now, if the caffeine is properly interacting with my neurons by now, You wish to do #4, but you are using the instructions for #3 to accomplish it. If I'm wrong, let me know and I'll switch to amphetamines.
If you simply wish to boot the stock Nook Color from the MicroSD card, there are pretty simple instructions here:
Run Android Froyo 2.2 from bootable SD card on Nook Color using Windows ? Step by step guide | Inspired Geek
If you actually want to root and/or flash a custom rom, then
Manual Nooter will give you root and
CyanogenMod will instruct you how to flash a custom rom.