Adobe Sign and Salesforce integration with custom objects

We have been using echosign for years integrated with salesforce. Now we are trying to implement for a client.

What we are trying to do: Send an agreement from a custom object using a custom email field. (The docs only show how to send to a contact from a custom object) we need to populate the recipient field with the value of a custom email field (the email recipient field appears to be able to accept a string).

We have done this before using conga composer and a url parameter (AdditionalTo), however we need to accomplish this without using conga composer)

Please let me know if this does not make sense.

Thanks,

Jason Burns