Really all a chimichanga is... is a deep fried burrito! So if you can make a burrito (flour tortilla filled with meat & cheese folded into a packet) and you've got a way to fry (deep fryer, good heavy pan & oil) you're golden.
Take a flour tortilla and add the fillings of your choice. Chicken or beef and cheese are good choices. Deep fry until crispy and brown. Serve with green chili sauce and shredded cheese on top.
The chimichanga is pretty simple to make. You will simply take a tortilla, fill it with some sort of meat or beans then wrap it up as a burrito. Place a toothpick where it will hold the burrito together and deep fry it.