You will need to use the 2.0 PCB, not 1.0.
NOTE: the schematic uses a 9.1V transistor, which could be difficult to find.

http://www.scantool.net/download/elmvpw20.pdf

You can check your vehicle to find out what data type it uses with the following link:

http://www.elmelectronics.com/obdstandard.html

On the ELM322 there is a mode called "Monitor All." Launch hyperterm and turn this mode on. Then hit the buttons you are interested in; any data on the line will show up in hyperterm.

Once you have that info that should give you an idea of what a packet looks like. There are a couple of things about the packet you need to know, for example addressing scheme of the packets. (physical or functional) I can help once you have an example of a data packet.

It would be worthwhile to grab the datasheet for the ELM322, and read it through. It’s written with hobbyists in mind and talks about all the different ways the chip can be configured. Its geared toward reading the cars ECU but you can read between the lines.

Will this work? It’s hard to say for sure until you have captured a packet. I think it should work fine; it will however take some creativity on your behalf. You don't need the chip to communicate on the buss, but it will make it a lot easier. If you don't use the chip your pic will need to deal with all the timing parameters for VPW and the CRC encoding and decoding. (not fun...not easy!)