Bro just buy a ticket to delhi or mumbai. Get off the plane, then buy a ticket to kathmandu from the airport or have some else buy it for you ahead of time in your name n have them email you the itinerary.

I hope you have your nepali naggrigta bc you will need that to get into kathmandu from india n get back to india. Dont use your passport. (you dnt need to)

From here to india use your passport and greencard.

This is the ideal way to do.

I dont think you should go with Funtush's advice (above me). When you land back here you dnt want to explain how things have changed in nepal therefore u traveled there. They might let you go but theres a chance they might start an investigation. So dont take that risk.