I used a little clip-on padded child-size toilet seat on the loo, along with a step stool for height. I didn't bother with a potty because that would have meant re-training with the loo at some point down the line and I couldn't see the sense of that. Mine were all on the petite side and we used the clip on seat for a good while -- until they each decided they were ready for bigger things.
For peeing the DDs sat down and DS stood on the step stool aiming at cheerios and small pieces of tissue paper ('fish').
I did leave a potty right outside the bathroom if I was going to be in there myself for any length of time, but I found it really, really messy, and never used it for the initial training period.
I followed a book called Toilet Training in Less Than a Day by Azrin and Foxx. It took about two weeks in reality, and there was a preparatory period that didn't involve using the loo, a dry run if you will. It was an intense two weeks and I was pretty much homebound for the entire period but it was a positive experience and it worked. I loved the method as it gave me explicit instructions and I felt I wasn't just poking along in the dark. An important aspect of the book was helping the parent/coach discern when the child was ready to embark on learning the new habit.
The focus was on keeping the pants dry rather than producing something in the loo, which if you think about it is what you are aiming for -- whatever goes in the loo goes there in order to keep the pants dry. I think focusing on producing something on the loo as the be all and end all makes children unduly anxious about that part of the process.
The book advocates taking off nappies altogether, night and day, once you get started and though that bit gave me qualms, I lined the little bed with heavy, cheap towels and took the plunge. The authors also pooh-poohed pull ups -- as a ^^pp said, this confuses the child. It also required the learner to be in charge of mopping up accidents and though that made me think of all the possible things that could go wrong it was clear as we progressed that it was a well-thought out aspect of the routine.