Customize Siebel Order Item in non-interactive mode

Hello,

I have a requirements to customize Siebel order items without opening the eConfigurator UI. For example, I have the following product configuration,

GSM Line (Root Product)

     - Voice Mail

     - Missed Call Notification

     - GSM Tariff 1

     - GSM Tariff 2

and I have Account who has the following installed assets,

GSM Line

     - Voice Mail

     - Missed Call Notification

     - GSM Tariff 1

I want either to be able to Modify the account installed assets and replace GSM Tariff 1 with GSM Tariff 2 using workflow or script and without opening the Configurator UI because the process will be called in back-end process and not by Siebel user, Or customize existing order and replace the items.