Using HTTP handlers and HTTP modules as services

You have been asked to create a set of web services. They will not be standard web services; they will be based entirely on HTTP modules and HTTP handlers. These services will be REST-based and need to support authentication.

What would be the most standard way to use HTTP modules and HTTP handlers to fill this need?
If you needed to add custom authentication, where would be the best place to put that functionality?
Do you think that creating web services in handlers and modules would result in a responsive application, or do you think performance would suffer? Why?