ADFS Deployment Guide - Sneak Peek #2 (Name resolution requirements for FSPs)
Detailed instructions for how to set up a federation server proxy (slated for the upcoming ADFS Design and Deployment guides) are currently awaiting technical review by the product team, so I can't divulge those finer details at the moment. However, I think it is probably OK to let you know (at a high-level) what two primary tasks you need to complete to configure the FSP for name resolution:
1.) Add an entry to the Hosts file on the FSP machine that points to the DNS Host name and IP address of the account federation server. An example of this, relative to the ADFS Step-by-Step Guide, would be:
192.168.1.3 adfsaccount.adatum.com
2.) Add a new host (A) record to the perimeter network DNS of the account partner that points the IP address of the federation server proxy to the DNS host name of the federation server. Relative to the Step-by-Step guide, this would be done by:
a. Using DNS Manager on the adfsaccount computer
b. Under the adatum.com forward lookup zone, add a new host record with the name adfsaccount and fill in the IP address of your FSP machine.
Hopefully this will give you a pretty good idea how to set this up until the updated Design and Deployment guide content is released publicly.