Screenshots are OCLC Connexion Client v.2.50, Koha v.3.12
To set up the OCLC Connexion desktop client to connect to Koha, go to Tools > Options, then choose the Export tab.
Click the "Create..." button to set up a new destination, then choose "OCLC Gateway Export" and click OK.
Enter the following information:
"Host Name:" Your catalog’s appropriate IP address (from your config file above)
"Port:" Your catalog's appropriate port number (from your config file above)
"Login ID:" The cataloger's Koha login
"Password:" The cataloger's Koha password
"Notify Host Before Disconnect" = checked,
"Timeout" = 100, "Retries" = 3, "Delay" = 0 (zero),
"Send Local System Logon ID Password" = checked.
Select "OK" when finished, and you should see your new "Gateway Export" option listed (The catalog's IP address and port are blacked out in the following screenshot)
Click on "Record Characteristics" and make sure that the bibliographic records are using MARC21, UTF-8 Unicode, and click OK to save.
You should be ready to go! To export a record from OCLC Connexion Client to Koha, just press F5 while the record is on-screen. The export dialog will pop up, and you'll see Connexion attempting to talk to Koha. You should get a message that the record was added or overlaid, including its biblio number, and a URL that you can copy into your web browser to jump straight to the record.