10.6.8 update crashed before it completed and now the Finder won't launch

Question

This morning I was installing the update on my 25" iMac 2.8 GHz Intel Core 2 Duo (was at 10.6.7) and after almost 15 minutes of the installer claiming to be moving files around, the screen went blank except for being backlit. After few minutes of pondering what to do, I restarted the computer and the "Finder quit unexpectedly." message started and all my iMac wants to do is have me send thousands of reports to Apple. I tried the safe restart and nothing changed expect the process number in the reports restarts in the low hundreds.
I have LOTS of applications on my dock and while most of the Apple applications (Safari, Disk Utility, etc.) crash upon launching, a few applications don't (Firefox takes a few minutes to crash while Chrome seems okay enough for me to send this report). The "About this Mac" claims that 10.6.8 is installed, so Software Update claims there are no updates, so I can't use that to reinstall the update (I'm not sure I should even if I could).
Because I cannot do is relaunch the Finder from either the Dock or via the "Force Quit" command I can't reinstall 10.6.8 via the. I can open a terminal window but I'm not sure what to do with that to get me out of this situation. I downloaded the combo update but without the Finder running, I don't know how to launch it via the a terminal window. Any suggestions welcomed.
TIA.

Answer 1

I've got my Mac back!
Even though the Finder wasn't running, because I had populated my Dock with dozens of applications, I was able to launch the Terminal app and open a window. From there I was eventually able to launch the Installer, point it at the 10.6.8 Combo Update (for some reason, fortunately, I had downloaded it rather than letting Software Update do it), and wait at least 30 minutes when the installer claimed that there was less than 1 minute left to complete the install. After it was done and I restarted the Mac, it no longer insisted that I needed to send/ignore thousands of "Finder quit unexpectedly." messages and the Finder was running.
BTW, towards the end of the installation (or re-installation), the Finder began to function (my desktop icons appeared and I could open folders) and now the only remaining issue is the Menu Bar won't appear unless I click the Finder in the Dock.
Thanks to those who helped me by providing the instructions needed to use the Terminal window correctly.