Now I know everyone in this world would love to get a chance to meet his/her idols 1-on-1 or be one of those cool select few who wear those "Backstage Staff" badges around their neck. Don't let those big security guards stop you from having your dreams fulfilled, I'll try to help you out.
First, you need to make sure that you and your crew are dressed to impress. No one wants to hang out with slobs or "the average Joe" (especially celebs). Once you have the 'money clothes', you need to get a group of people together of a good mixture of guys and gals (ideally 4-6). A tip, the more gals you have, the better chance you will have with the security crew (usually older men who hate being there because no one talks to them or likes them).
Look out for the key people such as the doorman, manager, or concert promoter / producer who are usually running back and forth around the ticket booth and the restricted door with 2 guards standing on either side of the entrance (and obviously wearing those special badges that all of you desire). These people hold the key to your dreams being fulfilled. Gather some money from your group (about $5-$10 from each person) and get the person who is the most gregarious (or hot) in your group to approach the gatekeeper. Remember, these people are trained to handle regular chumps who want to get in, so be creative. You will want to respectfully approach him, discretely shake his hand (with your roll of cash inside), let him know you traveled far with your friends here, and ask him if he would be so kind to let you meet your idol or tell you where everyone is going afterwards. I can tell you that these guys hardly get tipped like Las Vegas Doormen, so this will boost their ego and make them feel good (which is a good thing), and you will be in luck. Plus, they aren't all jackasses, so they won't just take your money and tell you to scram. They should hook you up one way or another.
If you get invited backstage, then you are half way there to the afterparty because that's what everyone will be talking about after the concert. If you find out where the party is, once the concert is over, head over there ASAP!!! After parties are usually not in the convention arena, and usually in a nearby club. You should be able to get in pretty easily because it will be early in the night and there won't be any lines. If there is a line or you get shot down the first time, go back to the doorman, discretely shake his hand (with your roll of cash inside), and ask him “about how long do you think it will take to get in.” He will usually respond “how many are in your group,” and will let you in within a couple of minutes (assuming you didn’t hand him an insultingly low tip) (Thanks to JackColton.com for the advice).
Your night with your group will be awesome because you will meet new people to join your group, enjoy an awesome concert, go backstage and meet your idol, and go to the same club where you will be less than 20 ft. away from his/hers private booth. Can't complain...