There are a couple of ways to get there.
First, if you are regularly associated with a team that is going or could be going pending results in qualifiers.
Second, if a team that is going is willing to take you on as a fill-in. But beware, this works best for elite pitchers; position players, or 2-way guys for whom pitching is secondary, often find themselves going all the way there to spend a lot of their 4 games riding the pine. I've seen teams show up with 25-30 players. You do the math; a lot of those boys go home unhappy.
Third, you can apply to PG to be placed on one of their squads. It can cost a bit more, but for a non-pitcher its advantage is that you know you're going to play nearly all the time when you get there. If pitching is important for you, you will, if accepted, also be assured of one multiple inning opportunity as well. Contact PG to inquire as to what you would have to do to get on a PG squad.