Here's a story on a company that creates a device to block only Fox News from your cable. And it appears that the cable provider has to install it for you if you ask. Here's the key article section:
"About a year ago, the National Cable & Telecommunications Association announced that a number of cable companies would offer channel-blocking equipment free of charge to any customer who does not possess that capability.
Now the FOXBlocker website exhorts supporters to ask their cable company to come to their home to install a device to keep out the Fox News Channel."
Seems like an interesting idea. It would demonstrate to the cable providers that you're unhappy with Fox News, making it a very explicit type of boycott. And if enough people start requesting the block, then some cable providers could even drop the station (I know, a long shot, but who knows?)
Here's the link to the full article:
http://www.boston.com/ae/media/articles/2005/04/14/hunting_for_fox_device_blacks_out_networks_news/