To be nice, the code should probably force a 1-second delay between checks but adamsnames doesn't have a restriction on that because the API is used by domain resellers.
Hope this helps someone. I've found it pretty useful as I'm particularly fond of two-letter domains.
Then I just pasted in this entire form:
Here's a modified example taken from a real one I submitted that got a response right away:
Two things to consider: Last time we bought domains (ri.ms and oh.ms) was in January. Also, we got a notice that they may not be selling MS domains anymore. If seeking .ms nowadays, the robot might not respond, I'm not sure.
As far as I know, you can only buy the two-letter domains using the email form on the adamsnames.tc site. Almost all of the registrars tell you that you're crazy to try to reserve a two-letter one. It's a little cumbersome, but I (and my company) have purchased literally a couple of dozen domains via the email interface on adamsnames.tc.
One other cool thing about adamsnames.tc is that you don't pay for the domains for a little bit after you order them. So you get invoiced and pay later after you start using the domain.
Edit: Reread your question: I definitely have ordered plenty of GD domains through their email interface. The fact that their site doesn't mention GD just reflects that they only added that tld in the past year. Helps explain why so few others have stumbled onto the trick I found for registering these.