Wondering for some that had problems if there isn't a sequence you have to follow.
Just installed lifetime subscription on Nuvi 660 with no problems.
Here's how I installed

Generated - USA, Total Traffic Network (US, CAN): 28992, 0, 0, 1 and entered generated code
POWER OFF THE UNIT & restarted the unit, so it starts fully in PRE BOOT MODE
Generated - Canada, Total Traffic Network (US, CAN): 31808, 0, 0, 1 and entered generated code
POWER OFF THE UNIT & restarted the unit, so it starts fully in PRE BOOT MODE
SHOWS
TTN (US,CAN): Lifetime Suscription

Generated - USA, NAVTEQ (US, CAN): 28935, 0, 0, 1 and entered generated code
POWER OFF THE UNIT & restarted the unit, so it starts fully in PRE BOOT MODE
Generated - Canada, NAVTEQ (US, CAN): 31751, 0, 0, 1 and entered generated code
POWER OFF THE UNIT & restarted the unit, so it starts fully in PRE BOOT MODE
SHOWS BOTH
TTN (US,CAN): Lifetime Suscription
NAVTEQ (US,CAN): Lifetime Suscription

Been using GPS for couple months now and it seems to work good