After much thought and discussion, I have a recommendation.
The Nemeth Code never did address computer notation, nor does the "Guidance for Transcription Using the Nemeth Code within UEB Context." Before the adoption of UEB, we used the Computer Braille Code.
I see that UEB Section 14 ("Code Switching") shows symbols for switching into "BANA Computer Braille Code" but BANA no longer supports use of that code. The point is made in UEB 14.1.1 that "non-UEB braille codes for subjects such as ... computer science ... is not necessary in UEB" although it does give the transcriber permission to have a "special reason" for switching.
You have been asked to follow UEB/Nemeth for this project. I interpret this to mean that you should switch to Nemeth for any math in the book, but the computer notation does not qualify as "math" and so you should follow UEB (The Rules of Unified English Braille) and UEBGTM (Unified English Braille Guidelines for Technical Material) for the computer lingo.
I have extracted a few points from UEB about this topic.
COMPUTER MATERIAL 10.12.3 ... "Use uncontracted braille for computer material, such as computer program code which is displayed on separate lines, as well as any nearby excerpts from the program."
Section 11: Technical Material
11.1 Introduction: "Refer to Guidelines for Technical Material when dealing with works of a technical nature, such as educational material in the areas of ... Computer Studies.
11.10 Computer notation: There is lots of information here.
"Guidelines for Technical Material" discusses computer notation in Section 17. Also, Hexadecimal numbers appear in 2.9.
I realize that this advice will put a screeching halt to your project as you do a complete U-turn. It is a relief, however, not to have to figure out how to present computer notation using the Nemeth Code.