# For *nix set up the options file for the serial port like this
options.ttySx # where x=0 for COM1, 1 for COM2, etc. See linux serial howto for more info
-detach
nocrtscts
local
proxyarp
SERVER_IP_ADDRESS:TIVO_IP_ADDRESS # e.g. 10.0.0.1:10.0.0.100
lcp-echo-failure 2
lcp-echo-interval 60
passive
persist
noauth
nodeflate
                                                                                
### and run 
#pppd 115200 ttySx &
#in one of your starup scripts (/etc/rc.d/rc.local)