CP Only through Proxy?

[kpdillon]

Is it possible to force CP only when users have a Proxy configured?  In my scenario I want to allow most traffic through by default, then when certain users have a need to goto certain websites they can fire up another browser that has a proxy configured that will force them to CP.

[eri--]

Usually there you do proxy authentication schemes.
But currently there is no possibility to do that with CP.