I'm currently coding an item that will open up inventories in other worlds.  The problem is that it doesn't work outside the dimension that you're currently in.  Not really sure where to go from here.

@Override
public boolean onItemUse(ItemStack itemstack, EntityPlayer player, World world, int x, int y, int z, int par7, float par8, float par9, float par10)
    {
	Block blockID;
	int blockX;
	int blockY;
	int blockZ;
	if(itemstack.getTagCompound() == null)
	{
		itemstack.setTagCompound(new NBTTagCompound());
		return true;
	}
	else
	if(itemstack.getTagCompound().getBoolean("hasSet") == false)
	{
		itemstack.getTagCompound().setInteger("BlockX", x);
		itemstack.getTagCompound().setInteger("BlockY", y);
		itemstack.getTagCompound().setInteger("BlockZ", z);
		itemstack.getTagCompound().setInteger("WorldNumber", world.provider.dimensionId);
		itemstack.getTagCompound().setBoolean("hasSet", true);
		itemstack.getTagCompound().setString("BlockName", world.getBlock(x, y, z).getLocalizedName());
		return true;
	}
	else
	{
		blockX = itemstack.getTagCompound().getInteger("BlockX");
		blockY = itemstack.getTagCompound().getInteger("BlockY");
		blockZ = itemstack.getTagCompound().getInteger("BlockZ");
		blockID = world.getBlock(blockX, blockY, blockZ);
		if(blockID != null)
		{
			WorldServer ws1 = MinecraftServer.getServer().worldServerForDimension(itemstack.getTagCompound().getInteger("WorldNumber"));
			if(!ws1.isRemote)
			if(blockID.onBlockActivated(ws1, blockX, blockY, blockZ, player, par7, par8, par9, par10) == false)
			{
				itemstack.getTagCompound().setBoolean("hasSet", false);
				itemstack.getTagCompound().setInteger("BlockX", 0);
				itemstack.getTagCompound().setInteger("BlockY", 0);
				itemstack.getTagCompound().setInteger("BlockZ", 0);
				itemstack.getTagCompound().setInteger("WorldNumber", 0);
				itemstack.getTagCompound().setString("BlockName", "");
				return false;
			}
		}
		else
		{
			itemstack.getTagCompound().setBoolean("hasSet", false);
			itemstack.getTagCompound().setInteger("BlockX", 0);
			itemstack.getTagCompound().setInteger("BlockY", 0);
			itemstack.getTagCompound().setInteger("BlockZ", 0);
			itemstack.getTagCompound().setInteger("WorldNumber", 0);
			itemstack.getTagCompound().setString("BlockName", "");
		}
		return true;
	}
    }

public ItemStack onItemRightClick(ItemStack itemstack, World world, EntityPlayer player)
    {
	Block blockID;
	int blockX;
	int blockY;
	int blockZ;
	if(itemstack.getTagCompound() != null)
	{
		blockX = itemstack.getTagCompound().getInteger("BlockX");
		blockY = itemstack.getTagCompound().getInteger("BlockY");
		blockZ = itemstack.getTagCompound().getInteger("BlockZ");
		blockID = world.getBlock(blockX, blockY, blockZ);
		if(blockID != null)
		{
			WorldServer ws1 = MinecraftServer.getServer().worldServerForDimension(itemstack.getTagCompound().getInteger("WorldNumber"));
			if(!ws1.isRemote){
			if(blockID.onBlockActivated(ws1, blockX, blockY, blockZ, player, 0, 0.0F, 0.0F, 0.0F) == false)
			{
				itemstack.getTagCompound().setBoolean("hasSet", false);
				itemstack.getTagCompound().setInteger("BlockX", 0);
				itemstack.getTagCompound().setInteger("BlockY", 0);
				itemstack.getTagCompound().setInteger("BlockZ", 0);
				itemstack.getTagCompound().setInteger("WorldNumber", 0);
				itemstack.getTagCompound().setString("BlockName", "");
			}}
		}
		else
		{
			itemstack.getTagCompound().setBoolean("hasSet", false);
			itemstack.getTagCompound().setInteger("BlockX", 0);
			itemstack.getTagCompound().setInteger("BlockY", 0);
			itemstack.getTagCompound().setInteger("BlockZ", 0);
			itemstack.getTagCompound().setInteger("WorldNumber", 0);
			itemstack.getTagCompound().setString("BlockName", "");
		}
	}
	else
	{
		itemstack.setTagCompound(new NBTTagCompound());
	}
        return itemstack;
    }

 

EDIT: Added the entire right-click event.

EDIT2: Added onItemUse

BUMP. can anyone help?

Diesieben07 is basically correct. Is not impossible, i have seen a plugin mod for Mystcraft that can load a second dimension and render the view. I don't know how he did it (my method was to render the view on arrival, save it, then transmit that data when it was need).

All I really need is load the exact inventory at the exact coords.  Like, somehow send a message to the server to load the dimension at that chunk, open the inventory, and send back that information to the client.  I'm not sure how to do that though.

You mean inventories of other dimensions?  I'll have to make it so players can't use the item unless they're in the same dimension as the inventory.

No, it works for all dimensions.  It just doesn't interact with things in other dimensions since the client only knows about one dimension at a time.