MLS and back from runlevel 3

[H S]

Hi 2 all, 
As the http://fedoraproject.org/wiki/SELinux/FedoraMLSHowto said: 

Configure the system to boot into run level 3 by default:

perl -p -i -e "s/^id:5:initdefault:/id:3:initdefault:/g" /etc/inittab

The when SE Linux execute MLS Policy instead of targeted, the system boots 
always in runlevel3 mode? 

I would like to run PostgreSQL DBMS based on MLS security policy. 
But when the system boot in runlevel 3, I have som problems. 

Is there any Idea that I come back to previous run level?
How ever when I did it, my screen was blinking, then I have nothing(black screen).
 
The system is Fedora 14, I have just installed
selinux-policy-mls-3.9.7-38.fc14.noarch.rpm. 

Regards,
Flora