Need to start system without it starting runlevel 5 and reconfigure X for new monitor. Couple of ways to do this.
One way, with LCD monitor connected, would be to have SuSE boot using failsafe option at boot menu. I'm don't use SuSE so not sure if it sets up a failsafe option. If it does, it should take you to runlevel 1. As root, do command 'init 3'. This should switch you to a mode where you have most of your services, but will not startx. At this point, start whatever utility SuSE provides to configure X, like Xconfigurator. Again, I do not know if SuSE installs that specific command, but give it a try. Once you've accessed whatever X configuration tool SuSE provides, configure you monitor for your LCD. Preferably the make and model but generic LCD will probably work.
Another method would be to edit the /etc/inittab file and change the line 'id:5:initdefault:' to 'id:3:initdefault'. Shutdown, switch monitors then boot up and get to runlevel 3 and configure X.
Another method, with CRT, would be to manually edit /etc/X11/xorg.conf and change the section for monitor. Only problem here is you need to know the specs of the LCD monitor, things like horizontal sync and vertical refresh rate. Here's an example:
ModelName "Samsung SyncMaster 910N/912N"
ModeLine "1280x1024" 108.0 1280 1328 1440 1688 1024 1025 1028 1066 +hsync +vsync
ModeLine "768x576" 50.0 768 832 846 1000 576 590 595 630
ModeLine "768x576" 63.1 768 800 960 1024 576 578 590 616
Yet another way, with LCD, would be to run the install disk but use the update option instead of install. Toward the end of the update, it should allow you to configure your monitor.
As you can see, there are several things you can try. Hope this helps.