I think it can only be done with code. Override your datasource's create() method and then call the button clicked() method. Note that to call directly the button's Auto declaration propery need to be set to Yes.
For instance in a SalesTable form you could overwrite SalesTable.create() method :
void create(boolean append = true)
{
SalesTable newSalesTable;
EditDetailsButton.clicked();
// rest code goes here
}