First announce a competition, but let your friends know when it wil end, but not anyone else. Then pull in some unknowns and people who do not have a clue what you are up to, to compete in the contest.
Advertise the contest and display the rules. Once started, just let everyone vote as per the rules and eliminate people as the competition draws to a close. Then allow the friends you want to increase their points comment bomb, and in the process get the other person in the competition comment bomb and increase their level. Now let this run until the specified finish time, and if the the person you want to win, isn't winning, change the finish date.
Then when their score is beating everyone else, close the competition. Now if your friends have comment bombed as requested, they should have a load of points and got to a higher level. Ok you have also increased the competitors friends points at the same time, but thats a by product.
All your friends who participated will praise you for the idea, and the person who won feels so wanted. Job done!
I just wish people who create competitions, would keep to the rules they set and not change them as they feel like it or because their friend isn't winning.