Even if you can't find the template, you can still do everything the training kit needs.
The only difference between an ASP.NET web project and an AJAX-enabled ASP.NET web project is that it takes care of a few pre-requisites for you:
1) It adds a reference to the Ajax control toolkit. You can do this manually by right-clicking on your project in the Solution Explorer, choosing "Add Reference", and navigating to the AjaxControlToolkit DLL (or find it in under the .NET tab, if you've added it to the GAC).
2) It adds a ScriptManager control to your aspx page. It comes with the Ajax Control Toolkit. The ScriptManager is required to use any of the AJAX Control Toolkit controls. Add it to the top of your page.
If you take care of those two things, you should be good to go - it's the same thing as using the Ajax-enabled website template.