The question was asked:
How do I load up an XSLT from the style library like:
1: XslCompiledTransform xslTransform = new XslCompiledTransform();
2: xslTransform.Load("/styles/file.xslt");
When I do this I get a (401) unauthorized exception
Answer
You need to use an XmlUrlResolver and populate the credentials property like:
1: XmlUrlResolver resolver = new XmlUrlResolver();
2: resolver.Credentials = CredentialCache.DefaultCredentials;
3:
4: XsltSettings settings = new XsltSettings(true, true);
5: transform.Load(XSLTUrl, settings, resolver);