I know it might seem like the TV is helping you to get laundry done or get dinner made- but if your son is that obsessed with it, then the TV is what is CREATING the bad behavior with your other kids, not helping you.
When my son was small, he watched maybe a half hour to an hour of tv, but not every day of the week. Ever since he was a baby, I have been told that he was remarkably 'self' entertaining- would sit and look at a board book, play on his own with blocks, etc. without having to be 'interacting' with someone else every second. Now he is 10 and still has a really great attention span, especially for a boy.
I am convinced that severely limiting TV at a young age is the reason for that! Your's son's tantrums just go to show how important the bright shiny world of tv has become to him. Do you really want him to be so focused on that? It may be that your other kids have different personalities and it isn't an issue for them- but for this one child, it is obviously a problem.
Don't let the toddler rule the house! It may mean a few unpleasant days, but I would just hang a sheet over the TV and tell the kids that it is 'broken' and they cannot watch it. Give them some safe toys to play with or let your son come and play with pots and pans in the kitchen or something while you make dinner- but BREAK THE HABIT.
Please trust me when I say it will only get worse. How you treat TV now is going to set the tone in the future for tv, video games, computer time, etc. If your son is already a junkie at a young age, it will be much much harder to keep his habits reasonable when he gets older.
Just suck it up and turn it off! If he bounces off the walls for a few days, then so be it. He will get used to not having tv and moderate his behavior, but only if you make the change. Good Luck!