I also am trying to get a block to be walk through. I looked at the vanilla blocks that are walk through, namely BlockTallGrass and it's super class, BlockPlant. Both have this:
public AxisAlignedBB getCollisionBoundingBoxFromPool(World par1World, int par2, int par3, int par4)
{
return null;
}
When I use this on my block, I can force my player into the block by having it in a hole, but when there is an open area to the side of the block the block pushes me into the open space. Anyone know how to fix this?