Most Linux distros include a term program called
minicom. The serial port settings will be the same 
as on a PC (I can't recall the speed, parity stuff). 
The only tricky part is when you want to move data back
and forth, like downloading some code. Minicom uses 
ascii-xfr for ASCII transfers and you'll need to customize 
the settings a bit to make it work with the IsoPod. 
Here's how:

In minicom, do an alt-a o to get to the config screen, 
then select "file transfer protocols" for the file xfer 
protocol settings. On the ASCII protocol, 
add "-l 200 -c 50" to the ascii-xfr program command line 
to get a 200ms line delay and a 50ms per character
delay (adjust the numbers to whatever you need).

Once you've got it working, you can usually lower
the delays and get much faster transfers but those numbers 
work even on the slow computers.


# Machine-generated file - use "minicom -s" to change parameters.
pu pname9           YUNYNascii
pu pprog9           /usr/bin/ascii-xfr -dsv -c 10 -l 10
pr port             /dev/ttyS0
pu baudrate         9600
pu minit            
pu mreset           
pu mdialpre         
pu mdialsuf         
pu mdialpre2        
pu mdialsuf2        
pu mdialpre3        
pu mdialsuf3        
pu mconnect         
pu mnocon1          
pu mnocon2          
pu mnocon3          
pu mnocon4          
pu mhangup          
pu mdialcan         
pu mdialtime        1
pu mrdelay          1
pu mretries         1
pu mdropdtr         0
pu hasdcd           No 
pu rtscts           No 



-R. Steven Rainwater-