Basically, it's not only about the command reward. You can rip from hellas/frozen the vote npc and simply remove the "vote button" from npc and use .getreward instead with the same exact check.
About what protect for net cafes you mean? Since, you can easily change your IP, it's more like a character based. Since, if you can't really check if your IP voted, someone else may vote instead of you and you get reward - no worries, it's only one time per char. But that way, you can vote with another player, but I wouldn't rly care about that, else there should be a hwid check.. So, you won't be able to cheat it :P