Download the correct SSIS version (v1.x is 2005, v2.x is 2008).
Unzip the file.
Open the solution.
Build the solution.
In an SSIS project, right click in the Toolbox and select "Choose Items..."
Under SSIS Control Flow Items, select Twitter Task.
You can then use the Twitter Task in your development.
For step by step instructions, see http://www.pragmaticworks.com/resources/webinars/April2010Webinar.aspx (SSIS Scripting and Custom Components).