The recommended way to override the updateLastLogin() method and create a new method called updateLastlmpersonation()...

Create a hook plugin and implement a service wrapper that overrides the updateLastLogin() method and creates the updatel_astImpersonation() method in the User service

Create a portlet plugin and implement a service wrapper hook that overrides the updatel_astLogin() method in the User service and build a new service in the plugin that references the User service and creates the updatel_astImpersonation() method

Create an Ext plugin that modifies portal-spring.xml to replace the User service with a new service that overrides the updatel_astLogin() method and creates the updatel_astImpersonation() method

Create a hook plugin and implement a service wrapper that overrides the updatel_astLogin() method and create an Ext plugin that builds a new service to implement the updateLastImpersonation() method for the User service.