How can I build a vanilla chunk loader without access to spawn chunks?

I have an iron farm on an SMP server. I want it to be loaded constantly. I know about the spawn chunk related methods (placing it there and hopper clock to there and back) but I can't build in the spawn chunks because they are rival territory. I heard about using a tamed dog to keep the chunk loaded; does that work? If not, are there any other chunk loaders that don't require spawn chunks?

I'm sorry to say, that currently using the spawn chunks is the only way to do it. I tested the Tamed Dog chunk loader myself and it did not work. For now, we will just have to wait until there is a feature or bug you can exploit. You could try AFK iron farming, although that is not recommended on all servers, so if you would like to know to do that I would recommend writing another question or editing this one. You could build up your power and take over the enemy territory though.