Translate or Add group email address during cXML Punchout Login Request

Hi All,

I'm trying to group my iProcurement users when they punch out to a particular supplier so that the supplier can customize content that shows on their catalog.  So far, I have not been able to find any discussion on mapping extrinsic values in iProcurement, but I would like to pass a translated email address to a particular supplier OR suppliment the login request with this group email.

Here's where we're at:

Oracle EBS 11.5.10.2
Vendor is Direct Punchout using cXML
OEXLoginRequest.dtd is currently passing employee emails, but a translation would look like this: 

Employee Email            LoginRequest Email (passed to supplier)