Actually User Replicator is a variant of ADC (At least it was in LCS) that takes information from the AD and replicates it to SQL and the only way to force it was and may still be through WMI. It was done by setting the MSFT_SIPUserReplicatorSetting, RegenerateCookiesNow to True (I don't have access to my OCS test server here, so I can't verify the setting in OCS here - ping me if you can't find it)
Usually the UserReplicator is really fast and it shouldn't be a problem in a test environment, but I have seen problems with it in large geographically dispersed enterprise installation, with slow lines and long replication times.