hot swapping

How do you do a hotswap, and how dangerous is it (if at all)?

If you are referring to hotswapping a BIOS chip in order to flash a dead one, you have to have the machine in question at the A: with a floppy with the flash utility and BIOS file ready to go on the floppy.
You would then remove the BIOS chip, and insert the one that needs to be flashed. Flash, and power down.

I have done this quite a few times, but only with the older style BIOS chips.

You must be very careful to insert the BIOS chip in the socket correctly, or you will immediately fry the chip, and possibly take the motherboard with it. You really should have a chip extracting tool. Having the good chip inserted lightly in the socket for easy removal is a good idea. I've read guides where they recommend a loop of strong tape on the chip to be removed.

Enabling BIOS cacheing in your CMOS settings beforehand is a good idea.

If the chip is for the same make and model of motherboard, it will flash with no problem.
If it is for another, the flash utility may detect a BIOS mismatch, and not flash. You may be able to get around this using the Uniflash, http://www.pppr.sk/rainbow/programs.html#UniFlash .

Here is a hotswap guide that may help if you have more questions, http://www.pppr.sk/rainbow/hardware/hotflash.html .

I have done it before, and I agree with Repo Man's explanation.

Have the good BIOS chip just lightly inserted into the socket, so that it is easy to remove. Once you remove it, lightly insert the bad BIOS chip into the socket. Be very careful that you insert it correctly or you could fry the chip or mobo. Don't use anything metal to remove or insert the chips. It is too easy to short something out.

My Asus board died and I was able to revive it by hotflashing with a Abit Nf7-S. Saved me the trouble of a RMA. Here is a tutorial for hotflashing. It is for a Asus board but the methods are the same for any board.