NetBSD with qemu/kvm "-kernel" option

[Assaf Gordon <assafgordon%gmail.com@localhost>]

Hello,

I have NetBSD-6.1.4 guest VM running under KVM (on amd64 host).
Works great with virtio disk and network.

Now I'm trying to take it to the next level:
Instead of using the bootloader inside the VM, I want to specify the kernel directly 
using qemu's "-kernel" option.

Generally, the usage is supposed to be this:
    kvm  -drive file=netbsd.qcow2,media=disk,if=virtio,index=0 \
         -kernel ./netbsd

Where "./netbsd" is the NetBSD kernel ELF file (stored as a file on the host 
machine).
Using the generic "netbsd" kernel does not work (VM doesn't boot at all).

I assume that more options are needed (e.g. "-initrd" and "-append"), and 
perhaps also a kernel with different options.

Does anyone have an idea of how to achieve this ?
Is rebuilding a kernel image from source with special options needed ?

Any help will be appreciated,
Thanks,
 - Assaf