Populate Z fields or extension on BAPI

Hi

I'm adding a sales order using VC, adds the sales order fine.

But now there are custom fields we have added in SAP on the sales order screen. Need to populate these trhough VC.

I'm using BAPI_SALESORDER_CREATEFROMDAT2, the custom fields are meant to be populated via tables paramter extensionin.

But the problem is I have to pass a structure type, then a structure with all the values. So if I did this in ABAP I would have a internal table and pass this along. How do I do this in VC???

Or is there another way to update these fields?

Thanks in advance