You can read the XML file and stick the result in some object that you register in the container during application start up. Your modules can then have that object injected.
That is; something like this in your bootstrapper:
public class Bootstrapper : DefaultNancyBootstrapper
{
protected override void ApplicationStartup(TinyIoCContainer container, IPipelines pipelines)
{
base.ApplicationStartup(container, pipelines);
var myXmlCacheInstance = ... // read your xml file and create an object to hold it
container.Register<MyXmlCahce>(myXmlCacheInstance);
}
}
and like this in your modules:
public class HomeModule : NancyModule
{
public HomeModule(MyXmlCache xmlCache)
{
Get["/"] => xmlCache;
}
}