Caveat: I think in hindsight Delmanntt is referring to the real **RETAIL** version of the DVD as purchased from Apple.
My post below refers to distros.
Just to put the cat among the pigeons:
I installed Hazard's 10.6.1-10.6.2 on my GX620 STRAIGHT from the DVD which I burned on my PC from the ISO WITHOUT going through all that rigmarole as described by Dellmantt. Sorry mate, don't mean to denigrate your hard work and very long post but it really was a piece of cake for me. One of the easiest and quickest intalls in fact. I even used TransMac to restore the ISO to a USB stick and installed direct from that too. (I expected a HUGE decrease in install time too, although to be honest it wasn't all that much faster, especially taking into account the time for the TM transfer.) However, for me, I'm still booting from Nawcom's ModCD every time as none of the B/Ls work for me - could be I'm doing something wrong as I'm very new to all this.
I also installed Hazard's 10.6.6i VERY easily too, from both DVD and USB stick, although I can't remember if I booted first before install from the ModCD. I'll get back to you on that.
Edit #1: deleted
Edit #2: My apologies, I didn't let it run long enough. Direct from DVD, it does indeed cause KP after about 45 secs of install. To overcome this, i boot first with Nawcoms's ModCD, swap discs, press F5, and install 10.6.6i from there, no special boot flags needed. The only prob for me is that after install has finished and it reboots to keyboard recognition screen, it won't recognise the USB keyboard and mouse (although I did check the USB3.0 and USBFix in Customise Install) and of course there are no PS/2 ports on the Optiplex. As a workaround, I simply take the SSD and boot it up on my ASRock/AMD 4200+ system which I usually use for Windows. Then after keyboard recognition and registering and it boots to the desktop, I shut down and just put the SSD back in the GX620.
I solved the no internet problem by uninstalling the BCM5751 kext, rebooting into BIOS, disabling the NIC, saving those settings, rebooting into MAC OS X, using Kext Utility to add the 5751 kext, shutting down, rebooting into BIOS, re-enabling the NIC, saving those settings, and booting into OS X. Bingo, interntet now works, IP address is correctly assigned.
In other words, and in short, installing the kext with NIC disabled in BIOS, then switching it back on again. No idea why it works but it does.
But I am definitely going to try Dellmantt's instructions for the Combo update without getting the KP at [PCI configuration begin].