This is included in the Optional Module needed for adding Tributes. See Tribute mapping for full details on how to map the Tribute record. Once you’ve done that, you can link the Tribute to the gift via the Tribute Gift Link. A sample mapping is shown below.
While you can use either a Source Field Name or a Default Value for the Acknowledgement and the Tribute Type, you can only select a mapping under the Default Value column for the Tribute and the Honor/Memorial. These will show your mappings from the Tribute tab as options.