Some help? How would you word it?
Well, I doubt anyone is likely to pick seven players from the old Soviet Union (or Yugoslavia), so in that sense it's (probably) academic in this particular draft. The potential problem here (as we saw in the last draft) is that "country of birth" or "country the player has represented" are ambiguous categories: Some countries (that were once football powerhouses) don't exist anymore, neither politically nor football wise.
The key, I think, is to be very precise (and then people may argue all they want that the rule is stupid or unfair, but at least there isn't any doubt as to what the rule IS).
As for this draft, you can make it easy on yourself by going for what you propose (which is also a classic draft feature - and a good one, in my opinion): No more than X players from one and the same continent on the pitch.*
* And for extra cover: This pertains to which country the player has represented in internationals. You can't feature X Europeans plus, say, Camoranesi. He may be South-American by birth, but he only represented Italy, so he counts as European. In the event of a player having represented multiple national teams on different continents, said player is a wild card and can be considered any way the manager decides. But the manager needs to make a call on the player once he's drafted. If he's European, he stays European throughout the draft. Should he be traded/picked up after his team is knocked out by a different manager, the decision is made anew by the new "owner" and the same principle applies (whatever is decided must he adhered to as long as the player remains in the squad).
This sort of pedantry has proven itself necessary time and again, which is why I'm making the point.