I am failing over to another SQL Server 2005 server, so you are correct that all that is needed is a change to the edasprof file from OLD_SERVER_NAME to NEW_SERVER_NAME in the line:
"ENGINE SQLMSS SET CONNECTION_ATTRIBUTES MY_CONNECTION OLD_SERVER_NAME\INSTANCE[...]".
I was just wondering if there was some "official" method to declare the 2nd server right in the edasprof file, so that if the 1st server is down, it would automatically try the 2nd without any human interaction necessary (like the SQL Native Client does). If no such method exists, I guess we can consider this question closed.
In case others using mirroing might be interested, as mentioned in my 4th paragraph, I did try making an Alert/Job on my mirror server that would run the following VBScript after a failover where it becomes the principal. It does accomplish the automated "find and replace" of the edasprof.prf file that I was hoping for (you'd want to change the filePath, OLD_SERVER_NAME, NEW_SERVER_NAME to match your setup):
filePath = "\\MY_WFSERVER\C$\ibi\srv76\wfs\etc\edasprof.prf"
Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objFile = objFSO.OpenTextFile(filePath, 1) 'Open For Reading
strText = objFile.ReadAll
objFile.Close
strNewText = Replace(strText, "OLD_SERVER_NAME", "NEW_SERVER_NAME")
Set objFile = objFSO.OpenTextFile(filePath, 2) 'Open For Writing
objFile.WriteLine strNewText
objFile.Close
Set objFSO = Nothing
WebFOCUS 7.6.11
Windows2k3/SQL Server 2005
Output: HTML, Excel, PDF