From nookDevs

Part of the NookColor portal

If you need to add a secondary Google account or need to delete a configured account, and noticed that the NC crashes in GMail when you click on account settings, this is the way to manually update the accounts.

To add an account, follow instructions at Drake22's post at AndroidCentral.

To remove an account, basically do the reverse; i.e.

1. Make sure you've enabled rw access to the system directory, and have adb access to your nc.
2. adb pull data/system/accounts.db
3. adb pull data/system/sync/accounts.xml
4. vim (or other newline-preserving editor) accounts.xml
   1. remove the lines with the account to delete
5. sqlite3 accounts.db
   1. select * from accounts;
   2. delete from accounts where name=''; (do not add a space between ' and your email address)
   3. select * from accounts;
   4. .exit
6. adb push accounts.db data/system
7. adb push accounts.xml data/system/sync
8. adb reboot