It should go in a directory called "parameters" in your server root directory (the one above the 'www' directory). It should be named the same as your servername, followed by an '.ini' extension.
Here's an example:
[ns/server/ncacasi/acs]
SystemName=NCA-CASI Network (C. R.'s install main)
; Debug the RP
DebugP=1
; Automatic Error Reporting
AutomaticErrorReportingP=1
[ns/server/ncacasi/acs/acs-developer-support]
; remember information about connections, for developers' benefit?
EnabledP=1
; Enabled on startup?
EnabledOnStartupP=1
; Enable switching users?
UserSwitchingEnabledP=0
; remember information about every database request?
DatabaseEnabledP=1
; remember information for which client hosts?
EnabledIPs=*
; remember this information for how long? sweep how often? (in seconds)
DataLifetime=900
DataSweepInterval=900
