You can solve this problem by having a central user database.
The switches can be configured with AAA for TACACS+ or RADIUS authentication.
You will need a server running Cisco ACS or any other RADIUS implementation.
Here is a quick rundown on how to do it:
http://www.cisco.com/en/US/tech/tk59/technologies_tech_note09186a0080093c81.shtml
Basically, you need Authentication and Authorization - Accounting is optional.
Regards,
Edison