But it is yet, Google has found the solution:
Time to look for it: "Installing Windows Home Server 2011 on a SSD in a HP MicroServer N40L"
Quick Start Guide:
On a USB flash drive (NTFS formatted) the cfg.ini file with the following content Create:
[WinPE]
ConfigDisk = 1
CheckReqs = 0
Windows Partition Size = MAX
I have the boot order to CD / DVD - SSD - ??? and USB Device Boot Priority eigestellt LOW.
Then booted from WHS 2011 DVD, with the stick in one of the front USB ports.
Installation started automatically and was finished after what felt like an eternity.
Because of the dimwitted (?) System requirements there a star less.