If you are using the Expanded translation scheme, you can use a Global Inbound Script to transform the HL7 message before it is translated, or a Global Outbound Post Process Script to transform the translated XML message:

For example, the following Global Inbound Script replaces the Patient Name in the PID segment (PID.5) with X's. The script assumes that PID is the second segment in the incoming message.

segments = value.split("\r")
PID_fields = segments[1].split("|")
PID_fields[5] = "XXXXX^XXXXX^"
segments[1] = "|".join(PID_fields)
value = "\r".join(segments)

After this script has been created, when a message is translated from HL7 to XML, the Surname and Given Name subfields of the Patient Name field in the PID segment are replaced with X's: