SetCustomProxy credential issues

Hi,

We have a client who use a custom proxy, and it's causing us a few problems.

I've attempted to use SetCustomProxy with the format 'http://host:port/', but it does not work.

However, if I use SetCustomProxy with the format 'http://username:password@host:port/' it does work.

The username and password I pass in here are exactly the same as the current user's username and password, so I would expect that it would work without having to explicitly specify the credentials. Is there a way that I can configure the TurboActivate proxy so that it takes the current user's credentials without me having to explicitly specify them?