Don't drink any beer any more myself, stopped drinking the stuff completely about 4 years ago, but I don't think folks are able to do that here. Well, there might be some small breweries that might allow it but mostly they just bottle their beer in Holland, I think.
Maybe in Belgium (they have a lot of breweries.. smaller/bigger), here and there, one can do it 'yourself'. I know in France, Spain and other wine producing countries it's totally common practice to fill up your own brought 'package' with p/m cheap table wines though. Wine, it being without the pop, is an easier product to do that with/duh.