ItemMobPlacer.java

/** @author Aesen Vismea **/
@Override
public boolean onItemUse(ItemStack itemstack, EntityPlayer player, World world, int x, int y, int z, int side, float hitX, float hitY, float hitZ) {
	EnumFacing face = EnumFacing.values()[side];
	int xO = x+face.getFrontOffsetX();
	int yO = y+face.getFrontOffsetY();
	int zO = z+face.getFrontOffsetZ();
	world.setBlock(xO, yO, zO, Blocks.mob_spawner);
	TileEntityMobSpawner te = new TileEntityMobSpawner();
	te.readFromNBT(itemstack.getTagCompound());
	world.setTileEntity(xO, yO, zO, te);
	return true;
}
// Example code to create an item for a Wither spawner
{
	ItemStack stack = new ItemStack(MyMod.MY_ITEM);
	NBTTagCompound tag = new NBTTagCompound();
	tag.setInteger("EntityId", 64);
	stack.setTagCompound(tag);
}