serial console is on ttyS1 not ttyS2
you had it, just change the "2" to a "1".1. What is the correct bootpage parameters on Series 3 Tivo's to stop the tivo applying software updates on reboot?
root=/dev/hda7 - duh...2. What does this command actually achieve. Is it stopping the software from actually being installed on the other partition or is it just stopping the other partition from being made active when a software update is installed?
dsscon=true - enables debug output on the serial console
console=1,115200 - sets console speed to 115200 baud on ttyS1
upgradesoftware=false - when your tivo boots, it checks for software in mfs other than /SwSystem/ACTIVE. if $upgradesoftware != false, then it initiates the install of the software, otherwise it just continues booting.
if you're not using a console cable for serial bash, then you can leave out the dsscon and console settings.