Today, I updated my previous helper class that replaced the standard RxUI service locator with Autofac container. ReactiveUI 6 introduced some breaking changes and I had to update the code to make it work.
Basically, RxApp has no method to register a custom resolver. Instead, it always uses the ModernDependencyResolver locator from Splat. However, this locator can work with any other type of resolver that implements IMutableDependencyResolver interface. There is one new member in this interface, ServiceRegistrationCallback, which is used nowhere in RxUI6 so I didn't bother implementing it.