Hi, I suppose you are using eBox 1.4, if not this is not going to be useful for you.
The support for object policies with different filtering profiles has been added recently, and it's still experimental, if you want to try it, do the following:
Edit /etc/apt/sources.list and and this line:
deb
http://ppa.launchpad.net/ebox/1.4-proposed/ubuntu hardy main
Then execute:
apt-get update
apt-get install ebox-squid
This will install ebox-squid 1.4.2 with the feature you want, but take into account that it hasn't been tested enough yet.
We will be glad to hear your feedback if you want to test it!