Below is a brief macro to automate inserting your 910 into NACO records. You're welcome to adapt for your own use. It reflects the current version of the cataloger instructions, using an upper case "NACO" in the signing string. The new version 1.1 also gives you options to record the number of records modified or created.
To use it, copy it into your Connexion macro directory (right click, save link as, and navigate to C/Program files/OCLC/Connexion/Macros). You may then access through the Connexion macros or assign it to a user tool for quick access.
When you call up the macro, select either the "New record" or "Revised record" button by clicking it, by hitting the first letter of the option on your keyboard, or by tabbing to your selection and hitting <Enter>. (Use <Esc> if you want to quit using the keyboard controls.) The first time you use the macro you may be prompted to enter the initials that you would like the macro to enter into the 910s it creates.
That's all there is to it.
NACO signing macro (version 1.1, December 6, 2012)
This page and macro by Jim Soe Nyun, last updated March 25, 2014