I'll try your suggestion about WowDoge.
That's what I did:
1. Get your private keys by following what I said above;
2. Open your notepad, paste your private keys (1 per line) and save it with the extention "any_name.key";
3. Open WowDoge and create a new wallet anywhere;
4. Go to "Tools" -> "Import Private Keys" -> Select the .key file you just saved above;
You should see your just imported addresses in the list. Just select the one you want to spend, click the big Send button and spend your coins!