I have the following:
4-node, 3-instance SQL 2005 64-bit Enterprise SQL cluster on Win2K3 64-bit O/S.
SQL instance install occured 8 mos. ago
Instance has been patched to SP2
Replication components not installed originally

Therefore if I attempt to configure distribution I get the following error: 21028:  Microsoft SQL Server Management Studio is unable to access replication components because replication is not installed on this instance of SQL Server.

I've already attempted the following: 
1. Control Panel/Add Remove Programs/Microsoft SQL Server/Change ... (failed, components already installed...)
2. Command line install to add replication to instance:
start /wait c:\...\setup.exe /qb VS=<VirtServer> INSTANCENAME=<InstanceName> ADDLOCAL=SQL_Replication (failed as well)
3. Setup.exe from media, modify existing instance (failed, components already installed...)

The issue seems to be that since Replication components are a sub-category of Database Services, and DB Services are already installed, the installation engine does not see that there is anything to upgrade.  There is also the issue that if I am able in some manner (with your help) to install replication components, that they'll be in RTM whereas the instance is at SP2.  Will the instance function long enough for me to upgrade the replication components to SP2?

So, how do I get replication components installed at this point?