No milk steamer or mocha machine
I would just heat it, either stove-top or microwave to 180-185º F, then whisk it like crazy to get some froth. It won't be like cappuchino foam, but should be sufficient for a latte.
If you have a French press you can put warm milk in it and shove the plunger up and down quickly until the milk is frothy.
Steam the milk, & froth it using one of those 1.99 aerators from IKEA!!
I was thinking about this after reading the question. Maybe a science or web source could supply a heat proof rubber stopper (the kind used in labs with a hole in the stopper that are used on flasks). One that fits in a tea kettle with a small length of copper tubing would make steam out of the tube. They make those stoppers with one hole or two holes.
Something like this.
with a short piece of copper tubing from hardware store.