According to Readium, MathJax.js single file version is based on MathJax 2.75 and according to its build script:
https://github.com/readium/MathJax-s...aster/build.js
That MathJax Readium version should already support TeX input (see the Readium comment line)
UPDATE
Edit:
I think I am reading that incorrectly. The first line specifies the use of TeX fonts not the TeX input.
So Readium has no TeX input support.