Resolution:
In this case it's InConcert 3.7 and MS SQL Server 6.5 running
on the saem NT system, and the customer wants to switch InConcert to use
an MS SQL Server database running on a different host.

The registry values to be changed are IC_DATABASE_HOST and
IC_DATABASE_NAME, found in HKEY_LOCAL_MACHINE -> SOFTWARE ->
InConcertInc -> InConcertServer -> &ltserver name>
-> Config and Settings
IC_DATABASE_USER and IC_DATABASE_PASSWORD will need to be updated
using the Configure option of the Server Manager.
(IC_RDBMS and IC_SERVER_DBMS should remain the same.)

In 5.x and above it becomes after SOFTWARE-&gtTIBCO Software Inc.-&gtTIB/InConcert Server->[Server Name]-&gtSettings.  The variable of IC_DATABASE_HOST  has been removed.