Originally Posted by jlightner
When you get the initial screen for boot select the default boot image (usually already highlighted) then hit "e" to drop into menu editing mode. Just add a "3" to the end of the existing boot line it shows and that tells it to boot into run level 3 instead of the default (presumably 5).
The default is specified in /etc/inittab like this:
You can change that 5 to 3 (after you've booted) so that subsequent boots while you're testing automatically start in run level 3 instead of 5. Don't forget to change it back to 5 when you're done.
This is really good chunk of information, thanks for sharing