Something that helps me, and I would expect a lot of others do, is to gear up and buff the heck out of your tank so they don't need to taunt. Get them to generate enough agro on their own naturally. Give the tank the good buffs, make them an agro machine.
If your just boxing a Tank/Healer, maybe add a dirge into the mix.
I will also agree, not letting the tank be completely box controlled is probably the easiest as well. You pull with a tank, it helps them establish early agro, they sorta of 'lead the offense' so to speak. As well, most boxes target through the tank, so controlling what the tank targets helps a lot.
This doesn't matter so much with older content for just leveling or power leveling, but once you get to the point where you are running current content that is a challenge and gearing up, you are going to want the finer grained control. I can't picture running a group of bots and being in control of a different bot that the tank.
Now one thing you can do, is setup MCP commands to have the tank use his rescue's and taunts. Have the tank do his normal CA runs and then press the MCP buttons when he needs to rescue or taunt (MCP should take preference/interrupt over the CA cycle). This is how I generally box and control my tank. The bot does the CAs, I move it, target the bot, and use MCP for the rescues, stoneskins, and other pieces. I am not sure how well you could control the tanks targeting choices from another toon.
Classic Coke