Replace banners and adcode on sites visited throught my proxies

I want to replace ad codes and banners on websites which are browsed through my web proxy sites. I want them to show my ads when users browse them through my web proxy sites. I want something like this site owner is doing.

http://www.vtunnel.com

All adsense ads change to some other ads when visited through this proxy site.
Is there a plugin or any code which can do the same for me??? Most of my proxies are running on glype but I can transfer them to any other script which can do this for me. Searched a lot on google didn't find anything so far

Just as a sidenote.
A year ago I asked google adsense support about this and they said it is a violation of their terms.
It is not allowed to modify the content of other pages to display your ads.

I wrote with them a few times and they were pretty clear about that fact.

Adsense code will not replace the site ads. I will use other network ads e.g. adbrite smowtion etc.

I know im resurrecting an old thread, but I would also like to know how vtunnel is replacing the ads on the proxified sites.

Any script that can do this for us?

yeah, me too.
I'm in the middle of something like that and looking for solution. I know it's doable because there are websites that use this method.
I have very basic skills of javascript and so far I was unable to do something usable. Meanwhile I've got anoter idea, to replace certain keywords with related affiliate links which is way much easier to implement. The problem is that proxy users are not so open for buying anything.

looking only at the technical site its quite easy to change what ever you want on a site the gets loaded though a proxy.
most of the webproxies use php remote file open or curl, so you already have the content of the sites as a string, all you need to do is use str_replace before the site gets delivered to the user.