There's no real built-in support for redaction in CMOD. You can build it, I think with the preview exit, and some heavy lifting on development. You'd want to redact-on-retrieval, so that the contents of the OnDemand archive remain accurate for legal / regulatory reasons. You don't mention data types, or if you only want to do this for metadata.
If you wanted to do it for metadata, you could play some database-side trickery - add an extra column for the redacted data, and then use a postprocessor script at load time to populate that field, replacing characters with dashes or asterisks something similar. Then you could do some folder tricks that woud allow you to search for a full field contents, but on retrieve, only see the redacted data.
There's some development involved, but it should be possible to build something that meets your needs.
-JD.