Installing a system to use both gjournal and gmirror

[perryh at pluto.rain.com]

I've read the Handbook sections on gmirror and gjournal, and the
gjournal-desktop article, and I'm still unclear on how to go about
setting up a configuration that uses both.

* Since I haven't started the installation -- thus the partitions
  haven't even been created yet -- it seems as if it "should" be
  possible to put the journals in the same partitions with the data.

* Since I can't mirror or journal a FAT32 slice AFAIK, and there
  seems little point in mirroring swap or /tmp, I think I want to
  end up with something along the lines of (on identical drives ad0
  and ad2):

    ad0                       ad2
     ad0s1 FAT32
     ad0s2 FreeBSD             ad2s1 FreeBSD
      ad0s2a <----- gm0 ----->  ad2s1a
                     |
   +-----------------+
   |
   |  ad0s2b swap               ad2s1b swap
   |  ad0s2c [whole slice]      ad2s1c [whole slice]
   |                            ad2s1d /tmp [same size as ad0s1]
   v
  gm0
   gm0s1
    gm0s1a
     gm0s1a.journal [gjournal label ad0s1a ad0s1a]  rootFS
    gm0s1c                                          [whole mirror]
    gm0s1d
     gm0s1d.journal [gjournal label ad0s1a ad0s1a]  /var
    gm0s1e
     gm0s1e.journal [gjournal label ad0s1a ad0s1a]  /usr

How do I go about doing something like this?