I've spent some time on implementing a hook for other authentication methods in qPad - kerberos, websso, you name it.
What I have now is an alpha version that can use external dlls for authentication (much like studio for kdb+ seeks and supports classes implementing IAuthenticationMethod).
Idea so far is very simple, I have a working qPad P.O.C. and dummy auth dll sample - please drop me a line (zakharovoleg@gmail.com) if you interested in implementing dlls for your organization's infrastructure and trying out this version. Of course, this version is free, just like the base qPad version

I tried to provide API as simple and transparent as possible, so there would be absolutely no need to pass usernames/passwords or other auth service details to qPad - authentication dll should take care of all that, giving out just temporary security token to qpad which it will in turn pass to server instead of plain text user:pass pair.
API's negotiable as well, but my goal is to keep it as generic/infrastructure-agnostic as possible of course.
Cheers,
Oleg