Things you need
1. Rice or Maize (Makaiko Jaad babal mmetho po huncha)
2.Yeast (You can get here easily)
3. Hay/Paral (Authentic parale banaune bhyea)[To Slow down the STEAM Process]
4.Momo Pakaune Bhada (best we can get here)

Recollecting from my Memory (correct be if I am wrong)
1. Rice ra Yeast mix garne  ani white cloth ma poko parne(i don't know the quantities) (may be 20:1) [See step 4, about adding Yeast]
2. Keep this on top of Paral. (hay is used to that only slight amount of steam goes to Rice and Yeast Mix)
3. Steam it for 1/2-1 hours !(can somebody confirm the time :-)]
4.take the content ( white cloth) (Nepal ko Suti(cotton)) [I guess Yeast are added while steaming or during this STEP , someone need to verify]
5.put that in air tight jar, fill with water.
6. let it be there for week or so
7. enjoy the drink.....

Try couple of time, you'll get it one way or the another!!