how to boot single-user mode?

[Ken Gaugler <keng@hybrid.com>]

Last night I tried and tried to get my system to come up in
single user mode (so I could do some major filesystem changes).
I couldn't get it to come up single-user.  I tried booting from
the original install boot floppy, and to my surprise it booted
up my kernel on the hard disk?!?!?!

I couldn't find the solution in the docs anywhere.  Can anyone tell
me what I should be doing?

For background, I need to change the size of some partitions, so
I need to copy whole partitions to a temporary location while I
re-do the partition table on the target disk.  I hope to avoid
having to re-install from tape or from scratch this way.

Thanks!