That is going to be a bit difficult, as the "All" means displaying the output from a bunch of different log files all at once.
I guess if you use Console to find the actual log files, you could then do something like:
for log in /var/log/system.log /var/log/secure.log /var/log/windowserver.log etc... do tail -f $log & done
This should start separate 'tail' commands for each of the logs and run them in the background concurrently. It might get jumbled up from time to time, but that is one way to approximate the Console All mode.
I guess you could write your own script to poll the different logs and control how they are displayed.