When system gets to the point "starting up X11 session manager" it just stays there. I cannont switch over to another
terminal or anything. It is set for init 4. How do I get in to resolve this?

You didn't give your distribution and release, so my answer is limited.

Watch the screen carefully when the boot process starts and go to interactive mode and boot linux single or type linux single at the very first boot prompt

When you get to the prompt you can try to configure your x properly

# Configuring X
Linux Hardware Compatibility HOWTO - video cards
The Linux XFree86 HOWTO
Common X configuring tools:
Debian - dpkg-reconfigure xserver-xfree86
Mandrake - XFdrake
Redhat 7.3 down - the setup utility leads to several config tools
Redhat 7.3 up - redhat-config-xfree86
You may have these tools:
XF86Setup
XFree86 -configure
Xconfigurator
xf86cfg
xf86config
xconf
ATI Linux drivers
If you need the nVidia driver, most likely, you want the Linux IA32 driver

Post details in your questions and fill out your profile to make it easier on us..

When I installed redhat 9 the default X server video driver was set up wrong. I ran redhat-config-xfree86 reset ( or something like this ). from the command line. This brings up a GUI that allows you to change the display settings. The problem I had was that the 3D acceleration was turned on . I turned it off and it worked. I think this utility is in ver 8 and 9 not sure about the previous versions

I am running Slackware 9.0. I changed the timeout to 0 seconds for lilo. Am I still going to be able to boot linux single?

Don't do that! You can't spare 10 seconds in life? Nope, you screwed up there.

Time to read up on your slackware rescue proceedure.
Most distros have a rescue feature on install CD 1 and they vary between distros as some mount stuff, some don't.

Basically for rescue, boot to a linux prompt, make a mount directory, mount the partition(s) you need to work on, make and save your fixes and re-boot. Edit your /etc/inittab and change the default runlevel to the number in the comments that is "Full multiuser mode" and you will boot to the command line (which always works unless you really really screw up) and configure your X. The command startx will then start the gui.

Any live CD or linux bootable floppy can be used.
KNOPPIX Linux Live CD
Linux Bootable Business Card
Tom's Root and Boot floppy