I have never done this before and someone else may have your answer, but these may help you figure something out.
xx MCK Message Cancellation Key
This key should only be programmed on Message
Center sets.
xx MIK Message Indication Key
This key should only be programmed on Message
Center sets.
xx MWK yyyy mwc-1
Message Waiting Key
Where: yyyy = DN.
The DN can be up to 4 digits, up to 7 digits with
Directory Number Expansion (DNXP) package 150.
With the Network Message Service feature
equipped, the NMS-DN can be up to 13 digits.
On the M3902, key 5 is reserved for MWK or NUL.
On the M3903, M3904, M3905, key 16 is reserved
for MWK or NUL
xx XMWK
xxxx yyyy
Extended Message Waiting indication key
Where:
xx= key number
xxxx = Message Center DN
yyyy = DN to be monitored
This is a Signature and not part of the answer, it appears on every reply.
This is an Analogy so don't take it personally as some have.
Why change the engine if all you need is to change the spark plugs.