Field 049 is used in OCLC only to record holding information in a subfield "L". Horizon does not use the 049 field for anything other than the subfield "L", and only accepts it on import. You cannot add an 049 field in Horizon.
When you are editing a record in Horizon that does not contain an 049 field, use a 945 field, subfield "a" to enter the information that will display in the CHICO HAS note.
The field that now holds item information is the 949 field (when exporting from OCLC only) [See Import Source Procedures for information on how to use).