XF 1.4 Using the Twitter API in a BBCode

[Case]

Given that xenForo already has integration with the Twitter API for user registration, is it possible to access it and use it in BBCodes? I'd like to create a BBCode that shows a users twitter avatar when you enter their twitter handle.

eg. [twitteravatar]username[/twitteravatar]

Is this possible? Any advice on where to start creating something like this would be appreciated.

Thanks