I still have pc's with a RS232 interface. But no max232 or something like that to get the dosonchip voltages to rs232 levels.
I tried to get it going with a software serial port on the arduino but it didn't work.
You could try the arduino's hardware UART (e.g. pin 0 and pin 1) - switch to external power (to disable the FTDI chip) and you can hook the dosonchip TTL level 232 to the arduino's TTL level 232.
-j