Well considering that I've been building entire operating systems that way for years now (by patching and compiling downloaded source code) that probably wouldn't be so hard to "accidentally" do for me.
And I wasn't entirely serious.
Fortunatly around these parts we have a bit different legislation, basicly I can do whatever I want with a signal that's beamed into my house unasked (at least last time I checked). Just as long as I'm not selling "solutions" like this I wouldn't be breaking any laws.
For me it would be more of a gimmick anyway, and since I'm not even allowed to pay for the few channels that I'm actually interested in as they're part of the SKY channel package, and I'm outside of the UK (although I should have no problem receiving the signal). So I wouldn't even feel the slightest guilt about it.
ldisplay was also kind enough to inform me in private where I could find more about these things. So the next time I'm bored and have a bit of spare cash to waste on some equipment I might look into it more closely, if only just for the fun of it. Anyway, thank you both for the hints, that should give me a good starting point.