This feature hasn't yet made it into a stable Windows release, but it's available in Insider builds, and the high-level client libraries and accompanying tests are on GitHub here:
Disclaimer: Remote Operations is still a work in progress. There's no public documentation yet aside from the README in the GitHub repo, and the client libraries aren't yet packaged for easy consumption. Moreover, this is not an official Microsoft announcement; I'm just bringing it up on this thread because it's relevant and I'm proud of this feature that I helped develop.
As an aside, how do you get to the bytecodeyou use? Do you write quazi-assembly by hand? Did you develop your own compiler? For what language?
Will other, non-microsoft assistive technologies, like NVDA for example, be able to use it?
As for how the bytecode is built, the GitHub repository I linked has a library with a WinRT API for building the bytecode at run time, by calling methods that correspond to the individual opcodes. It's an object-oriented API, so there's a class for each type of operand. And for control flow blocks (e.g. if-else and while loops), the method takes a WinRT delegate (basically a lambda) that builds the body of the block. You can see how it works in the functional tests; stay tuned for actual sample code.