Domains Using ASP

I have a situation where we have a mirror server located outside of our domain. Using ASP, I need to have the web server on the different domain access files on a file server that is within another domain and be able to display the file from the web page. They are Word documents and PDFs and Excel files. But for security reasons, we can not use anonymous access. On our production server we just use mappings within IIS to perform this, because it is all within one domain. I hope someone has had a similar experience and can tell me how this can be done using ASP or some kind of component.