Taking pictures of the moon using a 6" Dobsonian and a Nikon DSLR. What else do I need?

I own an Orion SkyQuest XT6. It's my first, and thus far only, telescope. I really like it. I also, separately, own a Nikon D3100. It's my first, and thus far only, DSLR. Both of these are things I've wanted for quite some time, for their own purposes, and now that I finally have them, I'm feeling the urge to combine them.

I know that Dobsonians are not good for astrophotography. I get that. I understand it fully. I need long-exposure times, and for that, I need a mount with tracking. Hopefully I won't get too into astrophotography, because it's just not a hobby I can afford.

But pictures of the moon... How hard can that possibly be, right?

So, should I buy a mount which enables me to attach the lens of my camera to the eyepiece of my telescope (like this) or should I buy a T-ring and T-adapter, which, as best I can tell, means using no eyepiece and no camera lens? I really don't understand how that would work. Which method should I use, and why?

Thank you, very much, for your help!