It was meant to be so easy.
Using httpwebrequest and httpwebresponse to pass loging credentials - and an App ID - to the facebook login.php page and get back the redirection string. This includes an auth code in the address parameters and would allow me to create a valid facebook session away from the site.
I have tried very nearly everything in my knowledge and I am no nearer solving the problem.
The problem, I think, is that although I am allowing the redirect in my code it isn't actually getting there.
Normally, on login, it loads the same page and then redirects to the correct page but the response I am getting back is still the login.php page...
I have a feeling there are some cookies involved so I might take a quick trip down that road and report back....
The actual reason for doing this is becoming lost as the ability to do it goes away so once I am in and this is working I hope I find a good reason to go with it....