@Kezza - of course, winner takes it (almost) all. UEFA makes their financial expenses somewhat transparent and there you can see how much money is earned for each step of CL (as well as EL, but we'll come to that point eventually).
Using this, developers can set their in-game financial framework and distribute the money according to rations used by UEFA.
It is more difficult for domestic leagues though. In Italy, for example, minor clubs joined in and tried to force major clubs to give them bigger share of TV rights. I don't think they've succeeded entirely and they never will.
Also, I like how every country is equal at the beginning (a team isn't better just by being from England). This may not be realistic but should work great :)