Like Andy, I use very large pots - about 10" wide, and make sure that there are a few inches of ordinary garden soil in the bottom, before topping up with new compost.
Hopefully, the toms aren't too leggy, but I try and bury them as deep as possible to encourage root growth up around 9" of stem below the surface. I've tried putting two plants in each pot to increase the yield, but am not really sure this actually works well, as they do get a bit crowded, so this year, they'll probably be on their own!
I also use those long watering trays which can take four of the pots - maybe even the buckets as above, and water them direct to keep them from drying out! I can never remember whether to feed from the top or from the bottom though...