Protecting identity - blocking System Fonts info

[notg]

Hi,
I'm new to Prox but I find it very powerfull so I decided it's the way to go.
I'm trying to make a filter that would replace the output of the fonts functions used by Java. I'm not concerned about the Flash ones at the moment as I only allow flash on websites I need.
Please just give me an ideea how to start, I'll find my way to the end and keep this thread updated.
As soon as I complete this as a proof of concept I plan to make filters for most used functions threating privacy rather than blocking specific URL's and cases.
Any help appreciated!