Zoho CRM Client script: how to load an external field from Create Page onSave event?

Zoho CRM Client script: how to load an external field from Create Page onSave event?

Hi everyone,

I need to keep Zoho's accounts synchronized with our internal ERP, so as a first step I'm writing a Client Script for the Account-Create-onSave event.
(I have to use a Client Script because the ERP may reject Zoho's submission because of business rules, so I have to stop the record creation on the Zoho side too).

Right now the script uses  ZDK.Page.getForm().getValues() to get the form values and then sends them to the ERP using a Connection. This works nicely and the ERP creates its own record for the new Account.
Now I need to store the ERP Account ID inside a Zoho external field, what is the recommended way to do this?
Is it possible to do it from inside the same Client Script?

Thanks in advance!