Connect Seeeduino Mega between 2 serial devices

Hi

I have a car OBD to USB cable , which i would like to see how works, by “sniffing” the data between the Atmega8L and the FTDI FT245BL chip in the cable.
How do i connect my mega, can i just connect the RX pin from the mega to the Atmega8Ls RX pin, and the same with the TX, or do i need to do it some other way?

The cable also have a little chip, with this text on it: ATMEL 93C56
Can i read out the data from it, using my Mega?

Datasheet of the Atmega8L
http://www.atmel.com/dyn/resources/prod_documents/doc2486.pdf

Datasheet of the FTDI FT245BL

http://www.ftdichip.com/Documents/DataSheets/DS_FT245BL.pdf

Datasheet of the Atmel 93C56
http://www.atmel.com/dyn/resources/prod_documents/doc3378G.pdf

Best Regards
Morten