The only way to set up a secret ballot would be to have a moderator for the forum conduct the election.
He would receive the votes, tally them up and announce the winner. He could also determine poster validity, etc.
Poster could not be affiliated with either major party etc.
That IMO would be the best way to do a secret ballot.
The biggest issue is who is completely neutral in this game? Realistically, I think that we have to have a secret ballot during the election, but the individual votes are made public following the election to ensure that there have been no counting errors.
Is there anyway that a page could be set up that would allow people to post in that section, but not view other responses (ie. votes)?
Another method could be to have two people running the election and use Google Forms. One would give every voter a unique ten character code, which the other, recording incoming ballots, couldn't see the codes before the end of the election and the person with the codes couldn't see the incoming votes. The complete data could be published after the election this way and neither would know who has voted before the close of the election. The tabulation would be conducted by both following the close of the voting booth.