Here are some step-by-step instructions on how to compile iTextSharp for use in a partially-trusted-caller environment such as that found on GoDaddy hosted servers.
Step 1. Download the source.
The source code is available here: http://sourceforge.net/projects/itextsharp/files/itextsharp/iTextSharp-5.0.6/
As of this writing, the current version available is 5.0.6. Newer source should always be available at this site.
2. Expand the ZIP file to get access to the C# Solution/Project files.
3. Open the Solution in Visual Studio.
You may be asked to convert the solution to the latest version of Visual Studio, accept the defaults.
4. Modify the AssemblyInfo.cs file (as discussed in the articles elsewhere in this site).
5. Build the solution and start working with your new DLL.
6. Generate PDFs for your site!