Installation on ARM-based Linux. FTDI driver

Hi guys, it's my first time posting here.

I'm trying to connect an Arduino to a TS-7400 board running Debian 6.0 on kernel 2.6.29-ts. It's an ARM 9 board.
At first I though it would be a piece of cake. Well, not really.

I can't find an FTDI-driver for ARM-Linux so I can't connect it though USB. I've been trying to go UART for the past hours but no luck. The Arduino and the board don't "link together". If my Arduino is haivng an active connection with a PC through the USB port, I can send command to it from the TS-7400 using the "echo" command. But when I unplug the USB, I can't send anything again. Plus, the doesn't "realize" there is something connected to the serial port.

Any known solutions? I could probably live without the Arduino on that project but we're using a IR library that we do not really want (nor have the time) to re-implement on the TS-7400 plateforme.