It's much easier to use an EBC in stead of a VBC.

Define an external table in tools. Define a new (external)BC on that table.

Create a new datasource in profile configuration (or, for dedicated client, in your .cfg). Specify this datasource on the table definition level,on the BC AND in the OM named datasources list. Now you can work with it (almost) as if it is a local table.

Disadvantage migth be that you can only access db's supported by Siebel (like oracle, db2, sqlserver). For other db's you probably have to resort to a VBC and sripting.