Some things I noticed (I did find some instructions on this forum), but they were spread out and sort of unclear. When using minicom to connect to your Tivo's serial port, here are some pointers.
1. Make your null modem cable (seriously, it took me 5 minutes, buying one would be overkill) using instructions located in the main dtivo howto.
2. Start up minicom on your Linux box like this $>minicom -s
This will launch you into your settings..use the down arrow to setup your serial port....keep in mind that most Linux'es use this format for their serial ports /dev/ttyS0=com1, /dev/ttyS1=com2, etc. I think Redhat uses /dev/cua. Also in the same settings there is a setting for port speed, parity,, stop bits, and byte size. Use these options....8N1 (that means 8 bytes, no parity, 1 stop bit), USE NO FLOW CONTROL. Set the port speed to 9600 initally. Hit ENTER to return you to the top level settings and use the down arrow to save this setting (you may use the "save as dfl" if you want these settings as the default settings). Use the down arrow to exit...Hit ENTER a few times and you should get a bash2.02#> prompt. If you do not then here are some reasons why.
3. Once you have the bash2.02# prompt make sure you optimize the serial port speed by typing bash2.02#> stty 115200 (this will disconnect you from the serial port, go back to step 2 and set your port speed to 115200 in minicom). You will be able to reconnect at this speed.
>>>>Your serial port may be locked up. If you attempt to connect to the serial port at a speed other than the speed the serial port on the tivo is set to, it could lock up the serial port. This requires a reboot of the tivo.
>>>>Your cable is bad (yes people make mistakes), check the cable with a mutilmeter.
>>>>You typed 'exit' at the bash2.02# prompt! This was the big one for me. DO NOT type exit when connecting via the serial cable. This will exit bash itself on the serial port and you will not be able to reconnect without rebooting the tivo. This is the best way to close out the terminal (minicom) hit Ctrl-A X and answer 'yes'. Your bash prompt should come back next time you start minicom.
>>>>Your serial port speed on the tivo is set to something other than 9600. Try 115200 or some of the other speeds.

From here you should be able to continue on like a regular bash prompt.