For which type of serial communication is Arduino Severino designed?
Looking at the schematic of that board it uses a very crude signal inversion for the RS-232.  This allows it to work of a standard RS-232 signal direct from a computer - just.

It's far from ideal and really should use a MAX232 (or similar) chip for the interface.

Your FT232 adaptor should bypass that chunk of the circuit and connect direct to pins 0 and 1 of the Arduino clone.  The DTR pin of the FT232 should connect to the RESET pin of the Arduino clone via a 100nF capacitor to allow the IDE to reset the board to enter the bootloader.  Oh, and of course, connect the ground to your Arduino clone too (something Arduino users often forget).

You can follow the serial breakout board portion of the Arduino breadboard tutorial and apply it to your board.