BITS Not Using Proxy Server

["alexander.jason@xxxxxxxxx" <alexander.jason@xxxxxxxxx>]

Hello,

I work for a large University and I'm having some issues with BITS as
it relates to Windows Update.

When the students come into our dorms at the start of the school year
they are assigned to a restricted vlan on our network.  This allows
them get get software that the university provides before they get
connected to the real network.  Like most universities all of our
address are in a public space.

One of the thing that we want to do is allow people to run windows
update before the connect to the real network to confirm they have all
the necessary patches. So do do this we've setup a MS Internet
Acceleration Server which seems to be working the way we expect it too.
 The problem I'm having is that BITS never  seems to understand that
there is a proxy server and it needs to use it.  I can see from my
packet captures that BITS is infact trying to directly connect.

Here is what I have tried so far to get BITS to see the proxy

1. Setup a manual proxy config in IE
2. Setup a proxy.pac file and served it to the machine
3. Did a proxycfg -u to import the IE settings in proxycfg

I've seen some other suggestions but they involved editing the registry
and other hacks.  I don't want to do with when student machines.
Ideally I would like to push a proxy.pac config and have both IE and
BITS work. 

Can anyone give me any suggestions.