Here is the problem I'm trying to solve: I have an Intel Mac Mini that I'd like to dual boot multiple versions of OpenBSD. I need to be able to boot into another instance of OpenBSD remotely and without a serial port, I had to come up with a way to choose which OS I want to boot to.
I installed OpenBSD 4.4-current normally on wd0a (wd0b = swap, wd0d = /tmp, wd0e = /var, wd0f = /usr and wd0g = /home).
Here is how I set the machine up with OpenBSD 4.3 installed on wd0h.