WikiHow. LyX/LaTeX is a word processing alternative that is completely
open source and free.
Summary:
With the incorporation of XeLaTeX in all major distributions of LaTeX
including MikTeX, it has become easy to incorporate Devanagari and
other Unicode characters in LaTeX/LyX documents. Here we describe a
point-wise summary to help you do just that.
http://www.wikihow.com/Create-Devanagari-Documents-in-Lyx-Using-Xelatex
Please help him to expand/test the how-to.