Passing parameters in the Twitter API URL callback

I've used OOB callbacks with desktop and mobile apps for twitter oAuth. But now I am moving to web authentication for my web app using twitter api.

I have the following stream of events:

• The user fills out the registration form (specifying n fields +), entering his email id and twitter.
• This generates a (short-lived) twitter request token and a URL to receive the tweet Access Token and secret.
• This url is sent to the user's email id, so it does the dual task of validating the tweeter handle and email id.

Now my question is:

Is it possible to specify a callback url with parameters so that when the user is redirected back to the application controller, the database gets n form field records?

And also how the user is redirected back to the app is the access token appended to the callback url (along with the parameters)? If so, how do I get the access token (token key and secret)?

To further clarify, consider the callback url:

http://www.someurl.com/controller?param1=val1¶m2=val2

and when redirecting to that url, i think (is it?) that twitter is adding some parameters to that url like http://www.someurl.com/controller?param1=val1¶m2=val2&someParamsAppendedByTwitter=someValue

I just want to know what it is someParamsAppendedByTwitter

.

The biggest problem with this question is that in almost all languages, twitter authentication is handled with some plugins / libraries, and there are very few resources if you want to do it all yourself.