I've made sushi rice before. You just need rice vinegar and some sugar, which you mix together so that it's neither sweet, nor tart...but you want to be able to sense both flavours in the liquid.

What I did was cook the rice as best I could, making sure not to turn it to mush (flushing the grains prior to cooking in cold water is an important step, by the way), but as you said, keep the grains firm, but a good consistency.

I then layed all of my rice out on a large rectangular plastic lid for some brownie tray or something. Then I sprinkled (not wanting to overdo it) the rice vinegar and sugar mix lightly over the rice, turning it constantly with a spatula coated in the mixture. When I had done it, I just knew it somehow. You will too.