erp5_upgrader can be used to upgrade any site:

 * Create Business Template and override TemplateTool_checkUpgradeConsistency script to set the Business Template list related to your project
 * Set extremely high business_template_skin_layer_priority (like 10000.0)
 * Develop constraints and set Constraint Type following upgrader steps
 * To upgrade site install first XXX_erp5_upgrader, then erp5_upgrader
 * Solve the alarm portal_alarms/upgrader_launch_full_upgrade