Well, i personally havent done this hook up yet (and with an 87 camry i kinda cant) but from what i know....
There is a converter from the OBDII to a serial connection.
There are many out there and i even read about one that i believe was USB.
Most that i have seen come with their own software for monitoring purposes. Also, if you check out the front end section, i have seen some who have integrated it into their set up. One had road runner displaying a speedometer and tach.
This probably wasnt much help, but i do know there are MANY on this site who have done it. You may want to check out the front end section for programming tips.