filipp.name

It's really quite simple when you know it. This is all also somewhere in the documentation, but here are the exact steps for easy reference:
1) Boot off the install media
2) On another machine that has the tools installed, pull a

/System/Library/ServerSetup/sa_srchr 224.0.0.1

That should get you something like this:

localhost#1.25 GHz PowerPC G4#192.168.0.114#00:11:24:3e:62:aa#Mac OS X Server 10.4#RDY4PkgInstall#3.0#512

3) Cool.

ssh root@192.168.0.114

Password: the first 8 characters of your server hardware's serial number

4) Set up the disks (if you have hardware RAID, remember to use megaraid!):

-sh-2.05b# diskutil list

/dev/disk0

   #:                   type name               size      identifier

   0: Apple_partition_scheme                    *37.3 GB  disk0

   1:    Apple_partition_map                    31.5 KB   disk0s1

   2:              Apple_HFS Mac OS X Server    37.1 GB   disk0s3

/dev/disk1

   #:                   type name               size      identifier

   0:    CD_partition_scheme                    *746.0 MB disk1

   1: Apple_partition_scheme                    649.6 MB  disk1s1

   2:    Apple_partition_map                    31.5 KB   disk1s1s1

   3:     Apple_Driver_ATAPI                    4.0 KB    disk1s1s2

   4:              Apple_HFS Mac OS X Server Install Disc 1 649.2 MB  disk1s1s3

/dev/disk2

   #:                   type name               size      identifier

   0:                        untitled           *467.0 KB disk2

/dev/disk3

   #:                   type name               size      identifier

   0:                        untitled           *95.0 KB  disk3

/dev/disk4

   #:                   type name               size      identifier

   0:                        untitled           *95.0 KB  disk4

/dev/disk5

   #:                   type name               size      identifier

   0:                        untitled           *95.0 KB  disk5

/dev/disk6

   #:                   type name               size      identifier

   0:                        untitled           *219.0 KB disk6

I want my install on disk0, also check that the disk is working OK:

-sh-2.05b# diskutil randomDisk 1 /dev/disk0

-sh-2.05b# diskutil eraseDisk "Journaled HFS+" Server disk0

Started erase on disk disk0 



Creating Partition Map

 5% ..

Formatting Disk                                                                                          100% ..

Finished erase on disk disk0 



Finished partitioning on disk disk0

4) Install (this installs everything)

installer -lang en -verbose -pkg /System/Installation/Packages/OSInstall.mpkg -target /Volumes/Server

5) Reboot. Run Server Assistant.