How do you populate the billing code field? What is the field name for the billing code?
The billing code is a profile element, and can be populated through the <ProfileInfo> portion of the UserCreate request. The element for billing code is "bill_code", so the XML would look something like this:
<ProfileInfo>
<ProfileItemName>bill_code</ProfileItemName>
<ProfileItemValue>the_desired_value</ProfileItemValue>
</ProfileInfo>