Change IP Address and not get detected?

so my friend just got into this contest and I gotta help him get votes,It's one of those vote for this person to appear in a local magazine.The contest says that they will be using a IP manager to help keep trolls from signing up under multiple names,I have to create different accounts and post comments and such,will they be able to know if I use a proxy or so or if I change my IP using software or anyother ways to change the IP that you guys might know?