Lee is quite a good one:
http://www.accesstoinsight.org/lib/thai ... ml#method2I'm also fond of Thanissaro's interpretation, which is getting at pretty much the same thing:
http://www.accesstoinsight.org/lib/auth ... 3.html#preThe state of concentration gotten through this method can definitely be used for vipassana. The mind is stilled to a large extent, but to the degree that focus and clarity are unobscured, not to the point of immobilization. Quite nifty. You can work on satipatthana or aggregate contemplation or mindfulness of the 3 characteristics or whatever, and if your mind gets dull you can take a moment off to rest in the tranquility of it.
One of the more important things I've found in establishing concentration is to really relax, but, you have to gauge how much relaxation is appropriate depending on your starting state of mind. You want relaxation that is conductive to mindfulness and alertness, not dullness. When the mind and body are really comfortable and unworried, palpably infused with ease, like the feeling you might get when you sit down in a comfy chair after a long day, it's a great foundation for deeper concentration.
Also I'll add, in the
Mystery of the Breath Nimitta article Moggallana linked to, at the bottom of it there's a little summary going over the initial stages of anapanasati. I find that for me, things happen exactly as he states. Give it a try.
( also, here's a good little composition on jhana that might be useful:
http://www.forum.websangha.org/viewtopi ... d78a309451 )