Emacs input method for Nepali with romanized Nepali keyboard layout of Madan Puraskar Pustakalaya, Nepal (or now, of Language Technology Kendra).
Load nepali-romanized.el file from your .emacs file. Then you should be ready to go.
See emacs-wiki-input-methods if you need help in setting/switching different input methods.
Select nepali-romanized to select this input method. You can use C-h I method RET to see the layout.
The keyboard mapping with the unicode is adapted from the one present at: https://github.com/suvash/nepalify/blob/master/lib/nepalify.js