I usually cheat and start with a pre-brined corned beef brisket (good sales right after St. Pat's day). I usually soak it in clean water overnight - change the water several times. Then slather on the mustard and liberally coat in fresh cracked black pepper and crushed coriander seeds. Then I cook it just like any other brisket on the KK, except that I usually use a milder smoking wood, like a hickory.
Starting from scratch, I'd brine it for at least 3 or 4 days, up to a week. Then continue as above for the rest of it.