EV Outlook Client to Remember last user logon domain and username

We are using Enterprise Vault, version 8.0, and accessing it from a non-trusted domain using the EV Outlook 2007 add-in.  The EV client log-on challenge requires authentication, since our computer log-on domain is different.  However, the EV client log-on challenge does not display (or cache) the domain\username once it has successfully been entered, as does our Outlook log-on challenge (since Exchange email is also in an untrusted domain). 

Can you change the EV client (I believe we're using the HTTPS client) to cache that domain\username, so once it's correctly entered during an EV client challenge it is always then pre-populated\displayed in subsequent EV log-on challenges?

We do understand we can manually create a user, under our Windows desktop OS and tie that to the EV domain, but that's a manual process for thousands of users.  If the EV connection\client process could take care of that, the user experience would be much improved.