There is a way to do it. I did it at the Buffalo NPPL a few years ago.
You can't use real money. You would have to set up a site where people get 'P8ntballer bucks'. They get some with a plat membership or something. They can bet using their P8ntballer bucks, and then the guy with the most bucks at the end of the event gets a prize, or is just crowned the awesomest winner on the site.
That much can be done.
The issue is the odds, you really need someone with a really good grasp of odds to run it. I didn't have any odds-on bets so people ended up with millions of dollars because they could split and hedge their bets.
If using real money odds work in two ways:
1) the odds of something happening, there are 3 results to a single game of any kind - win, lose or draw
With no other knowledge then each is a 1 in 3 chance of each result, in practice probably less draws. In some games there can be no draw, so it becomes 50/50
2) the bookies risk
This starts with basic odds, then adjusts to how people bet
If everyone bets on the one result the bookie pays out nothing or more than he has earned
The bookie adjusts the odds so that any payout is less then his total incoming, if it gets risky he makes the same bet with another bookie - so that if he pays out then he has income for it, if he does not pay out then he has lost his bet, but he offset the risky odds
Rather than all this if you want to bet real money then put together a sweepstake-And pay out all the money (check gambling laws)
If you don't want to use real money then go online for a fantasy sports website
I've had a chat with a few mates that own online bingo/gambling websites and they suggested you would need stats built up over a year or two to actually do the maths of odds on teams etc. Something i'm keen on though.