I've always used a contact printing frame, but I've just come back from a Michael A Smith workshop where he demonstrated this technique. Foam pad, paper, negative, sheet of clean glass, thick card to start and stop the exposure, and a household bulb in an anglepoise lamp. It really was that easy - for him anyway - perhaps a bit harder for me :-)

If your paper is on a foam pad then you can lower the glass down from one side pressing the negative against the paper as you go. That way you don't have to drop the glass the last tiny bit as you'd have to if you're on a hard surface.

And yes, the emulsion side needs to be pressed quite firmly against the paper to get a good contact. So a heavy sheet of glass is best (or a good spring back frame).