Take a look at Assisted Company Setup in MAS 500.  It has staging tables (like stgSalesOrder) for importing data.  You'd just populate the staging tables then call the appropriate API.  You should be able to trace to find anything you need.

You could leverage spARapiCustomerIns which pulls data from stgCustomer and stgCustAddr. There is an Import Utility for Sales Orders on the SO Utilities menu. Review spSOapiSalesOrdIns which pulls from stgSalesOrder and stgSOLine.

Thanks for the reply.