Thanks to both for your responses.
I don't think that search engines shouldn't see this like a manipulative action, but maybe they do and we'll be banned.
Thomas, I couldn't use a GeoDNS because I think that GoogleBot always come from an US IP, so it will only index and rack our US domain. This is the reason for try to identify GoogleBot and don't make the redirect, I Google had a spider with an IP of each country we shouldn't have this problem, but think that this isn't suceed.
We'll use ccTLD for each one, so Webmaster Tools assign the country automatically.
Best regards,
Robert