sure thing. the scolari one is a little weak, but you could make it difficult if you worked your way from the depths of the llower divisions up.
I'm more than willing to have the Walter one flexified, but Yours is really, really good, apart from maybe the sheer enormous scale of the thing

I did have another idea, and I have to thank you for it, because yours was the inspiration for it.
Cross-Continental challenge.
Win a trophy from each country in one continent, then take a lower ranked country from that continent to the world cup final.
for example, in europe, you'd go through scandinavia, into the british isles, win a trophy from each country there then head to portugal, then spain. into france, then belgium, Holland and Germany, into austria, then italy, into greece, poland, russia, and then finally, stop in finland, then take your EU country national team seat.
If you're really suave, you'll be able to win a cup in one country then flit to another. but, if you take it at 1 country a year, it'd take...22 seasons, but that's without flitting from team to team mid-way through a season, also, remember that the scandinavian leagues run at different points....
It's a gargantuan challenge, but it's not impossible, but it is perhaps a little too much