I was looking at the migration yesterday and you don't have to be on 4.0 you just need to buy and enter the 4.0 up grade then the migration keycode this will regenerate all the codes to the 450 platform if they were in the KRS.If not you need proof ,auth code or purchace order.
This solution allows migration of purchased software licenses from any BCM1000, BCM200 or BCM400 to another BCM1000, BCM200 or BCM400 system. For example, a customer wishing to migrate from an End of Life BCM1000 platform can now purchase a new BCM200, BCM400 or BCM450 system and an Application Migration Authorization Code, thereby preserving their previous investment in enabled keycodes. This also provides Nortel distribution partners with an exciting opportunity to renew the installed base to currently supported hardware and software consistent with current Lifecycle Management policies. If the destination system is a BCM200/400 at 4.0 software there is no need to purchase a BCM 4.0 upgrade keycode separately. When re-generating the keycodes on KRS, just specify 4.0 as the desired keycode format for the re-generated keycodes. If the destination system is a BCM450, a BCM 4.0 upgrade keycode will be required if the source system is at a software release prior to 4.0.
The solution entails purchasing an Application Migration Authorization Code via standard catalog ordering procedures, and utilizing this keycode in conjunction with KRS to provide regeneration of application capabilities between BCM systems
Return of either the source MSC or System (with MSC card) hardware will be required to avoid charges for equivalent application capability costs. Either a Nortel RMA number or Serial number of the returned hardware will be required at time of migration/regeneration.