Well, what I'm used to at least is taking my fiddy, putting street tires on it and whalla, a mini-motard bike. You can have the same motor configs you have for your dirt bike. Obviously the tracks are paved. Some tracks I've seen are just in parking lots outlined with chalk, some are really nice with banks and curvies, the whole enchilada.
Riding style might be a bit different. Although I've seen a lot of dirt riders transition to motard wihout changing their style. In the corners for motard you generally lean way in, almost scraping your knee on the pavement while keeping your bike in an upright position. In other words, you lean one way, the bike leans the other. A lot of dirt riders will simply put their foot out around corners the same as when they take corners in dirt. I've seen pretty fast riders use either style.
On a side note, what I'd really like to see is a mixed track with dirt and motard. What a great way to show off a fiddies capabilites!