how to access a variable from the InnovatorServerConfig.xml file inside a c# method.

From my POV this one is one of the best customizations you can do cause it´s helps improving security. I once got this tip from another community member:

XmlDocument xml = CCO.Cache.GetCacheInfo("ApplicationXML");
string reportServerURL = xml.SelectSingleNode("//ReportingServices/ReportServer").InnerText;
string reportUser = xml.SelectSingleNode("//ReportingServices/User").InnerText;

...

Thanks Angelalp for your quick response.

It is working fine.