You can use a script if else branch by using a normal Conditional Branch event command and then choose "Script..." on the last page.
Otherwise I think the best thing is to use variables such as
x = $game_player.x
y = $game_player.y
$game_map.passable?(x, y, 0)
But there is no legal workaround for making it bigger in any way.
There are patches for it but as I said, they aren't legal. If I remember right at least.