Looks like to me you installed the system onto the disk, but wrote the wrong
kernel image into the PReP boot partition.

> Now comes up the NetBSD kernel! Oh yay! Except, it's panicked! Oh no!
> Same screen as before.
> >> NetBSD/prep BOOT, Revision 1.5
> >> (builds@build, Mon Dec  6 00:12:27 UTC 2004)
> 
> Boot: Loading in()
> 3537044+185960=0x38d160
> start=0x100000
> 
> panic: lockmgr: no context
> 
> The operating system has halted.
> Please press any key to reboot.

This is not the patched kernel. The patched kernel will show the build 
signature as something like "(build@Zimbo, xxx Jan 24 xx:xx:xx UTC 2005)".

Try to install the patched kernel image to the disk:

Boot your machine off the CD and get a shell at the first prompt. Then 
run

	# dd if=generic_com0.fs of=/dev/rsd0c 

again and run

	# fdisk -u -1 sd0

to recover the MBR (re-enter the numbers you entered previously). After this
is done, run `fdisk sd0' and disklabel sd0` to verify the MBR and the disklabel 
are fine (the same as what you saw when you installed the system).

Rongsheng