Create a Filter on the Stats tab. Set the Tournament Score formula to "points". Set the Overall Score formula to "sum(top(n-2, scores)) + (n - 2 - count(scores))".

The first part, "sum(top(n-2, scores))", sums the player's scores and drops the lowest 2. The second part, "(n - 2 - count(scores))", awards the player 1 point for any tournament he didn't participate in, excluded the 2 that were dropped. So if your league has 10 tournaments, and a player plays in 6, he'll get the sum of those 6 tournaments, plus 2 additional points, one for each of the 4 he didn't play in minus the 2 that were dropped.