Update July 10, 2012 - Tweetbot 2.4.1 was released today. This update removes the settings panel required to complete this tutorial. If you want to keep your custom settings, do not update to Tweetbot 2.4.1 or higher.
Jailbroken users can keep their customized settings on Tweetbot 2.4.1 by following this tutorial from @ReagentX.
A few days ago, a secret settings panel was discovered in Tweetbot, a popular Twitter client for iOS. One of the settings in that panel was for changing the Consumer Key and Consumer Secret the app uses to authenticate with Apple. Most people didn’t know what that was for. Most still don’t. And those who do seemed to be having issues getting it to work. Well, thanks to @dakotadallen, I’ve gotten it working on my phone, and I’m going to show you how to do it, too. All you’ll need is Tweetbot (iPhone, iPad) and a Twitter account.
First, go to http://dev.twitter.com and sign in using your Twitter account. Once you’re logged in, roll over your username in the upper-right corner and click on “My Applications”.
Next, click on “Create a new application” and choose a name for the app. This is what will be displayed as the client name when people look at your tweet. You can change this later if you want.
Next, enter a description and a website. Neither of these will be seen by anyone, so you don’t really have to put anything real in these boxes. Just make sure your website starts with http:// and your description is at least ten characters long.
The last block, the callback URL, is very important. If you skip this step you won’t be able to login with Tweetbot. If you accidentally skip this, it’s OK. You can always go back and fix it later. (This is the part Dakota helped me with, thanks!) For the callback URL, just paste this link: http://localhost.com/twitter_login.php
Finally, fill in the captcha, agree to the terms, and click the button to create your application.
Now we have some more work to do. This stuff is easy though. If you’re redirected to a list of your applications, click on the app you just created. Then click on the Settings tab. Scroll down to the section called “Application Type” and set it to “Read, Write and Access direct messages”. The rest of the info on this page is totally optional. Next, click the save button and then go to the Reset Keys tab. Hit the button to reset your keys.
Go to the Details tab and scroll all the way to the bottom. There should be a button that says “create my token” or something similar. Click it.
We’re almost done now, I promise. The last thing to do is put the appropriate codes into Tweetbot. Open up Tweetbot on your iDevice and go to the settings page. Scroll all the way to the bottom and tap both of the bottom corners simultaneously three times in a row. This will open the secret settings.
The top section is where you’ll need to put in the codes from Twitter’s site. Go to the Details page of your newly-created app and look for the Consumer Key and the Consumer Secret. Don’t share these codes with other people. Just put those numbers EXACTLY as they appear on the page. I found it was easiest to just email them to myself and paste them into Tweetbot.
After that, there’s one last step. Go back to your account in Tweetbot and try to refresh the Direct Messages tab. It will tell you to login again with Twitter. You’ll notice when you login again that instead of asking you to login to Tweetbot, the webpage that appears is asking you to login to the app you just created. Type in your password and hit the blue button. Send a test tweet. You should be good now. You’ll need to login on all of your accounts again. There is no way to have each account use a different client name, so if you run any parody accounts or whatever, they’re also going to use the client name you just chose.
If you get an error that Tweetbot couldn’t contact Twitter, there are two possibilities. You either typed in your Consumer Key/Secret wrong, or you forgot to set the callback URL (or you typed it wrong/included an extra space).