Stopping dtlogin From Running Without Doing L1-A?

It depends on how you started dtlogin and if you want to be 
permanently out of dtlogin or not. 

If you did a /usr/dt/bin/dtconfig -e to enable dtlogin to start each and 
every time you boot your machine, then from the login screen, pull down on 
the Options button and select Command Line Login. 

If dtconfig has enabled dtlogin to run all the time, you will be presented 
with a command line prompt (after pressing the return key when indicated) 
and can do your command line login and subsequent work. Once you log out, or 
if you fail in your login attempt, dtlogin will restart. 

However, if you never enabled dtlogin through dtconfig, you will be a 
victim of a code fix to avert a potential security hole in the login 
process. Whereas the previously discussed option used to be available
from the login screen, someone could use this mechanism to break the 
login process with a Control-C, thus dropping them into your system 
as root, something that should not happen. So, if dtlogin is executed from
the command line, the Command Line Login is specifically disallowed. 
The thought is that, whether or not you agree with it, to run dtlogin, 
one must do a dtconfig -e to enable the new login process. 

Aussuming that you will only run the login configuration script, to get 
out, you can still use Control-C, but you have to use it after 
the logout process has completed (you'll usually see all those apps in your
workspaces map to the screen and then have the screen blank). Once the 
screen goes blank, you can press the Control-C to abort the dtlogin process. 
It's not pretty, but it does the job you want. 
 
To disable a permanent dtlogin from the command line (as root) do: 

/usr/dt/bin/dtconfig -d 

to disable the recurrent dtlogin screen. A reboot might be necessary after 
disabling dtlogin through dtconfig to make the system understand that the 
removal of this process is permanent.