Consoles: Toggling Internal vs. Serial during boot

[Joe Altman]

The relevant system specs: FBSD 4.10, one serial port.

I've read the docs:

http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/serialconsole-setup.html

I am pretty sure I understand it all, but for one part. I'm not quite
clear on how to grab the internal console once serial bits are set
up. What I mean is that I'll compile the kernel with:

device sio0 at isa? port IO_COM1 flags 0x30 irq 4

and in /boot.config use:

either -D or -Dh or one of the -P options. But in any of these, I'll
end up with only serial access once in kernel.

Section 17.6.6 Changing Console from the Boot Loader seems to be the
relevant section. Is it really as simple as putting

set console=vidconsole

into /boot/loader.rc? I don't think it is; but if so, what do I type
(and when) to grab backthe video console? Is this a job for
loader.conf and flags, at some stage in the process of booting?

In the situation available to me, I can have access to a KVM and a
console server. So, I'm thinking ahead, and planning to have the video
console available to me if I break something. I'm pretty sure I won't
need it and can rely on the serial console output; but is there a way
to toggle (during boot blocks or boot loader) away from serial to
video output?