downgrade 7.1 to7.0

[Kris Persson]

I am using "7.1-RELEASE FreeBSD 7.1-RELEASE #0: Thu Jan  1 08:58:24 UTC 2009
root at driscoll.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  amd64 "

I would like to downgrade from freebsd 7.1.x to freebsd 7.0.x  I am using a
3ware controller for my raid drives.  I have never done a freebsd downgrade
before and would like any recommended steps or how-to's so I can accomplish
this without a wipe and reload.  Thanks Kris