This is what ogre is for. None of us play more than one character full-time. Some folks play their wizard or their assassin or their <insert-non-tank here> because it's what they like, and automate their tanks. The tank really isn't different than any other bot:
1) Learn the class - its spells, its CAs, its AAs, its prestige, and any special clickable items
2) Develop an effective casting order, separating out what belongs in the priority tab from what belongs in the CA tab. For tanks, pay special attention to taunts and temps. Use the priority tab to fire off temps to stay alive or to grab aggro.
3) Use the MCP to your advantage. Create special buttons for RESCUE and death prevents and other emergency spells and CAs, and use them when the fight is getting out of control.
4) Figure out where to position the auto-tanks for each fight. Are they un-campspotted so they're next to your main tank? Are they campspotted in their own special spot away from the main raid force?
5) Figure out targeting for each fight. Are they targetting through you, or do they need to use AutoTarget for the fight? Here's a hint: for boar, your OT(s) need to AutoTarget the adds while your MT is handling the Boar full-time.
Ogre is your best friend. Learn it, love it, live it.