How to make custom ribbon on existing workbook using VBA and without downloading other software?

Question

Problem:

I would like to be able to edit the ribbon on a single workbook and place my own tabs and macros within the custom ribbon. Obviously I don't these tabs to show on other workbooks etc (there are few rules, see below section)...

Rules

1. Ideally I want to be able to do it without downloading anything. My work place is crazy strict with downloading from the outside world. (but I might be able to do it fromm home if its the best way).

2. I need to be able to do it on an existing workbook, there are just to many graphs/formatting/data/macros within the workbook to move everything over to a new workbook.

3. Ideally it needs to be a very repeatable/Safe/Reliable method, this workbook is a massive work in progress so I will probably be coming back to it and adding more tabs/macros as the months go by.

Previous attempts

I have tried working with the custom UI briefly in the past. People suggested things like downloading the custom UI editor? I think that I managed to sort of start editing an existing sheet that had the custom UI within it already. But I could not figure out how to increment this into an existing workbook very easily.

FYI I am very familiar with VBA but not HTML...

Can anyone give me a few quick steps that I need to do or is there some documentation out there? I did try looking but couldn't find anything....

Cheers